HWH 700 Series User manual

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 1of 39
SERVICEMANUAL
FEATURING:
HWH CORPORATION
(On I-80, Exit 267 South)
2096 Moscow Road | Moscow, Iowa 52760
Ph: 800/321-3494 (or) 563/724-3396 | Fax: [phone]
www.hwh.com
700 SERIES AIR LEVELING SYSTEM
HWH COMPUTER-CONTROLLED
R
R
R
NOT IN
BRAKE
PARK /
TRAVEL
MODE
CAUTION!
SECURELY BEFORE REMOVING TIRES OR CRAWLING UNDER VEHICLE.
UNDERSTAND OPERATOR'S MANUAL BEFORE USING. BLOCK FRAME AND TIRES
DUMP
RAISE
STOP
EMERGENCY
TRAVEL
MODE
SLOPE
EXCESS
HWH COMPUTERIZED LEVELING
LEVEL AIR

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SECTION 1
SECTION
2
FIGURES
SECTION
1
TROUBLE
SHOOTING
GUIDE
2 PART FOLDER
HOW TO USE MANUAL
This manual is written in two sections. Section 1 is the Trouble Shooting Guide. Section 2 is the figures. Begin diagnosis of
the system with Section 1, the Trouble Shooting Guide. The Trouble Shooting Guide describes system operation with each
phase of operation followed by symptoms of possible problems. The problem section is broken up into 3 columns,
Problem, Solutions and Figures. Under Problems, find the symptom you have encountered. The testing and repair for that
problem is in the Solution (center) column. Diagrams for a particular Problem and Solution are in the Figurines (right hand)
column. This column will direct you to the proper figure in Section 2, Figures, for a more detailed view.
Before beginning your repair, it is IMPORTANT to read the CAUTIONS and NOTES AND CHECKS in the first section,
TROUBLE SHOOTING GUIDE. In many cases this will save time and mistakes when trouble shooting a system.
This repair manual is offered as a guide only. It is impossible to anticipate every problem or combination of problems. For
any problems encountered that are not addressed in this manual, contact HWH Corporation for assistance. (800-321-
3494)
PROCEED WITH TROUBLE SHOOTING GUIDE

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TROUBLE SHOOTING
CAUTIONS!
BLOCK FRAME AND TIRES SECURELY BEFORE CRAWLING UNDER VEHICLE. DO NOT USE AIR SUSPENSION
TO SUPPORT VEHICLE WHILE UNDER VEHICLE OR CHANGING TIRES. VEHICLE MAY DROP AND OR MOVE
FORWARD OR BACKWARD WITHOUT WARNING CAUSING INJURY OR DEATH.
DO NOT EXCEED 5 MPH OR TRAVEL LONG DISTANCES WHEN THE SUSPENSION IS NOT AT THE PROPER RIDE
HEIGHT.
SAFETY GLASSES ARE TO BE WORN TO PROTECT EYES FROM DIRT, METAL CHIPS, OIL LEAKS, ETC. FOLLOW
ALL OTHER SHOP SAFETY PRACTICES.
NOTES AND CHECKS
Read and check before proceeding with Trouble Shooting Steps.
NOTE: HWH CORPORATION ASSUMES NO
LIABILITY FOR DAMAGES OR INJURIES
RESULTING FROM THE INSTALLATION OR
REPAIR OF THIS PRODUCT.
1. The trouble shooting guide must be followed in
order. Problems checked for in one step are
assumed correct and not checked again in
following steps.
2. Batteries should be in good condition and fully
charged. Low voltage can cause erratic operation.
Important: Not all vehicle air suspensions are
plumbed the same. Consult the vehicle
manufacturer for specific plumbing diagrams.
Also, not all vehicles employ the speed switch
to latch the “DUMP” or “RAISE” buttons in.
These systems will have momentary “DUMP:
and “RAISE” buttons.
This manual is intended for use by experienced mechanics
with knowledge of air suspension and automotive electrical
systems. People with little or no experience with HWH leveling
should contact HWH technical service (800-321-3494) before
beginning. Special attention should be given to all cautions,
wiring, and air diagrams.
Suggested tools for trouble shooting the HWH leveling systems:
JUMPER WIRES(UP TO 10 GAUGE)
MULTI-METER
12 VOLT TEST LIGHT
PROCEED WITH THE TROUBLE SHOOTING
STEPS ON THE FOLLOWING PAGE.

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CONTROL IDENTIFICATION
"EMERGENCY STOP" BUTTON
"EXCESS SLOPE"
"NOT IN PARK"
RAISE RIGHT SIDE BUTTON
LOWER RIGHT SIDE BUTTON
LEVELING LIGHTS
(4 - Yellow)
WARNING LIGHTS
(4 - Red)
RAISE REAR BUTTON
LOWER REAR BUTTON
"AIR" (ON) BUTTON
DUMP LIGHT
"TRAVEL MODE" BUTTON
"TRAVEL MODE"
LEVELING SYSTEM
"DUMP" BUTTON
RAISE LEFT SIDE
BUTTON LOWER LEFT SIDE BUTTON
RAISE FRONT BUTTON
LOWER FRONT BUTTON
LIGHT
LIGHT
CAUTION!
HWH COMPUTERIZED LEVELING
UNDERSTAND OPERATOR'S MANUAL BEFORE USING. BLOCK FRAME AND TIRES
SECURELY BEFORE REMOVING TIRES OR CRAWLING UNDER VEHICLE.
NOT IN
PARK /
BRAKE
DUMP
RAISE
EMERGENCY
STOP
AIR
TRAVEL
TRAVEL
EXCESS
SLOPE
RAISE LIGHT
"RAISE" BUTTON
"TRAVEL MODE" BUTTON
LIGHT (Red)
HARD RESET SWITCH
(SEE HWH LIGHTED RESET SWITCH)
MASTER WARNING LIGHT
ACTIVE LIGHT
LIGHT (Green)
MODE
MODE
CONTROL FUNCTIONS
CONTROL BUTTONS INDICATOR LIGHTS
“AIR” BUTTON: This is the system active and
automatic operation button. It woks if the ignition is in
the “ON” position.
“EMERGENCY STOP” BUTTON: This button turns
the system OFF but does NOT control power to the
“DUMP” or “RAISE” buttons. Pushing this button will
NOT put the system in the TRAVEL mode.
“TRAVEL MODE” BUTTON: This button will put the
Leveling system in the TRAVEL mode. The ignition
must be “ON” for the vehicle to return to proper ride
height for traveling.
“DUMP” BUTTON: This button will lower the whole
coach by dumping air from the suspension system.
“RAISE” BUTTON: This button will raise the whole
coach by adding air to the suspension system.
IMPORTANT: Read “DUMP AND RAISE
FUNCTIONS” before using the “DUMP” and “RAISE”
buttons.
UP ARROWS (RAISE BUTTONS): These
momentary buttons are used for manually operating
the air leveling systems. Sides or ends of the vehicle
will raise while these buttons are pushed.
DOWN BUTTONS (LOWER BUTTONS): These
momentary buttons are used for manually operating
the air leveling systems. Sides or ends of the vehicle
will lower while these buttons are pushed.
LEVEL SYSTEM ACTIVE LIGHT: Flashes during automatic
leveling and sleep mode.
DUMP LIGHT: Flashes when “DUMP” button is pushed.
RAISE LIGHT: Flashes when “RAISE” button is pushed.
“EXCESS SLOPE” LIGHT:ON if the leveling system can NOT
level the coach.
“TRAVEL MODE” BUTTON LIGHT (RED): Light flashes for 3
seconds after the “TRAVEL MODE” button is pushed.
TRAVEL MODE LIGHT (GREEN): ON if the ignition is in the
“ON” position, the system is not being used, and there is
sufficient air pressure in the suspension.
WARNING LIGHTS: Function with the ignition in the “ON”
position. ON when the LEVELING SYSTEM ACTIVE LIGHT
flashing.
LEVELING LIGHTS: One or two yellow lights can be on
indicating the side, end or corner of the coach is low.
“NOT IN PARK/BRAKE” LIGHT: ON while the “AIR” button is
being pushed if the Park Brake is NOT set. The light will go out
when the “AIR” button is released.
MASTER WARNING LIGHT: ON any time the “TRAVEL” light is
not ON, if the ignition is in the ON position.

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PART 1 –700 SERIES SYSTEM OPERATION
This section is a description of the touch panel and how the system works, automatically and manually along with a
description of how the “DUMP” and “RAISE” buttons work. If you have a good working knowledge of the system,
skip ahead to the diagnostics. If you are not familiar with the system, it would be a good idea to review this section.
The 700 series air leveling system is a computer controlled BI-AXIS push button system. The system has one touch automatic
operation or can be controlled manually. The system will always raise or lower two corners of the vehicle at the same time, in
automatic or manual leveling.
The buttons and lights of the touch panel are briefly described on the previous page. The ignition must be in the “ON” or “ACC”
position for the “AIR”, “DUMP”, “RAISE” or the manual UP and DOWN arrow buttons to function.
Pushing the “AIR” button one time starts the automatic leveling sequence.
The “TRAVEL MODE” button will take the system out of automatic leveling, SLEEP mode, a DUMP procedure, or a RAISE
procedure and return the system to the TRAVEL mode. The vehicle will return to ride height if the ignition is on and there is
adequate air supply.
The “CANCEL” button will stop the automatic leveling process,SLEEP mode, a DUMP procedure or a RAISE procedure but
WILL NOT return the system to the TRAVEL mode. The vehicle will not return to ride height.
The “DUMP” button will exhaust air from all of the air bags to lower the vehicle and the “RAISE” button will add air to all of
the air bags to raise the vehicle. These two buttons will function if the park brake is not set. They will be explained in greater
detail later.
The UP and DOWN arrow buttons on the right side of the panel are for manual control. The manual UP and DOWN arrow
buttons will function anytime the ignition is in the “ON” or “ACC” position as long as an automatic leveling process has not
been initiated or the system is in the SLEEP MODE. Pushing an UP arrow puts air in the air bags, raising the vehicle and a
DOWN arrow button will exhaust air from the air bags, lowering the vehicle. Pushing an UP or DOWN arrow button will always
control two corners of the vehicle both front, both rear, the right front and right rear and the left front and left rear air bags.
The blue LEVELING SYSTEM ACTIVE light above the air button will flash slowly if an automatic leveling process is in
progress and flash rapidly when in the SLEEP mode. When in the SLEEP mode, this light will continue to flash rapidly even
when the ignition key is off. This light will only flash for auto level and the sleep mode and should never be on steady.
The blue light above the “TRAVEL MODE” button will flash a few times after the “TRAVEL MODE” button is pushed. It will
not continue to flash nor should this light ever be on steady.
The four red WARNING lights at the corners of the manual UP and DOWN arrow buttons will be on steady anytime the
LEVELING SYSTEM ACTIVE light is flashing or if the “DUMP” or “RAISE” buttons are being used if the ignition is in the “ON”
or “ACC” position.
The four yellow lights between the WARNING lights are the level indicator lights. A lit yellow LEVEL light indicates that that
side or end of the vehicle is low. One or two LEVEL lights can be on but never opposing lights. The yellow LEVEL lights can
be on if the ignition is on and the park brake is set.
The “NOT IN PARK/BRAKE” light will come on if the “AIR” button or the manual UP or DOWN arrow buttons are being
pushed with the ignition on. The system will not function in auto or manual if the park brake is not set. The “NOT IN
PARK/BRAKE” light will also come on if the “DUMP” or “RAISE” buttons are being pushed but those buttons will function with
or without the park brake set.
The “EXCESS SLOPE” light will be addressed when we discuss an EXCESS SLOPE situation during automatic leveling
The green “TRAVEL MODE” light will be on anytime the ignition is on if the LEVELING SYSTEM ACTIVE light is not flashing
or the RAISE or DUMP lights are not on.The front air manifold will have a 20 psi pressure switch to monitor the air bag
pressure for each side. The rear air manifold will have a 20 psi pressure switch to monitor the air bag pressure for each side
and an 85 psi pressure switch that monitors the system air pressure. If the ignition is on, the park brake is off and a pressure
switch is on, the TRAVEL MODE light will not be on.
Note: Some vehicles may have two air bags for each corner plus one air bag for each side of the tag axle if so
equipped. For ease of discussion we will refer to the “left front air bag”, “right front air bag”, “right rear air bag” and
“left rear air bag”. If the vehicle has an arrangement of two air bags for each side of an axle, these bags will simply be
teed together, acting as one. Tag axle information will be addressed separately when necessary. For most systems,
the tag axle will mirror what the drive axle is doing for leveling purposes.

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AUTOMATIC OPERATION
It is best to leave the engine running for the automatic leveling procedure. The ignition must be in the “ON” or “ACC” position
to initiate automatic leveling. The park brake must be set. If not set, the “NOT IN PARK/BRAKE” light will come on while
pushing the “AIR” button and the system will not function. One or two yellow level lights may be on at this time.
Pushing the “AIR” button one time will initiate the automatic leveling sequence. The LEVELING SYSTEM ACTIVE light above
the “AIR” button will start to flash. The system will first exhaust the air from all of the air bags, even if no yellow level lights are
lit.If all level lights are off after the dump cycle, the system will go immediately into the SLEEP mode. When the last air bag
pressure switch is made, the processor will determine the high corner of the vehicle. The lower valve load for that corner will
remain on during the complete leveling process and remain onuntil level is achieved with all yellow level lights off or until an
EXCESS SLOPE situation is encountered. The rest of the lower valve loads will be turned off. At this time, the auxiliary air
compressor load will be turned on and like the high corner lower valve, will stay on during the complete leveling process. At
this point, all leveling will be achieved by raising a side or end of the vehicle.
The processor will always level side to side if necessary before leveling the vehicle front to rear. If a front and side level light is
on, the processor will turn the side raise loads on until the side light turns off. After a two second pause, the processor will turn
the front raise loads on until the front level light is off. If the side level light comes back on, the system will ignore that light until
the front light goes out then the processor will turn the side raise load back on until the side level light goes out. When all four
level lights are out, the vehicle is level and the processor will go into the SLEEP mode. The LEVELING SYSTEM ACTIVE light
will now flash rapidly. This will continue until the “CANCEL” button or the “TRAVEL MODE” button is pushed. Releasing the
park brake with the ignition on or off will cancel the SLEEP mode and turn the LEVELING SYSTEM ACTIVE light off.
If only a front or rear level light is on when automatic leveling is initiated, after the initial lowering of the vehicle, the system will
first try to level the vehicle from front to rear. If a side light comes on during the leveling procedure, when the front or rear light
goes out, the system will raise the side for the leveling light that is lit.
FLICKERING YELLOW LEVEL LIGHTS. When an active level light flickers during the automatic leveling procedure, the
system will pause until that light comes on or turns off for two seconds then continue with the leveling process as needed.
Here are a couple examples.
Scenario 1: The front and left side level lights are on. The left side raise loads are on, lifting the left side. If the front level light
flickers, the leveling process is not interrupted. The left side continues to rise. If the left side light flickers, the process stops,
turning the raise loads off, until the light comes on solid or turns off for two seconds. If the light comes on solid, the raise loads
for the left side turn back on and will continue to raise the left side until the light goes out and remains out. If the light flickers
and then stays off, the processor will move to the front level light turning the raise loads for the front on until the front yellow
light goes out.
Scenario 2: The front and left side level lights are on. The left side raise loads are on. The left side level light goes out. The
processor turns the front raise loads on and starts lifting the front. The left side level light comes back on. The processor will
ignore that light until the front level light goes out. The front level light flickers. If the front light turns back on solid, the
processor continues to raise the front until that light remains off. If the light goes out for 2 seconds, the processor will go back
to the left side level light,turn the left side raise loads on and keep them on until the left side level light goes out. If the front
light comes back on, the processor would go back and try to turn the front level light out.
SLEEP MODE
SLEEP mode happens only if automatic leveling has been used. The processor will put the system in the SLEEP mode when
all the yellow level lights are out in the automatic leveling process. The LEVELING SYSTEM ACTIVE light will start flashing
rapidly. The ignition can be turned off and the system will stay in the SLEEP mode. Thirty (30) minutes after the SLEEP mode
is initiated, the processor will wake up and monitor the yellow level lights. If any yellow level light comes on solid, the
processor will initiate a leveling procedure. The LEVELING SYSTEM ACTIVE light will flash slowly. Depending on lit level
lights and air bag pressure switch conditions, the processor may do a lower procedure before starting the normal level by
raising the vehicle procedure. Once leveling is achieved, the processor will return the system to the SLEEP mode for thirty (30)
minutes. The LEVELING SYSTEM ACTIVE light will again flash rapidly.
EXCESS SLOPE
EXCESS SLOPE is a timed sequence. Very simply, approximately fifteen (15) minutes after the “AIR” button has been
pushed, if any yellow level light is on, the EXCESS SLOPE light will come on and all loads will turn off. The EXCESS SLOPE
light will remain on until the park brake is released or the “TRAVEL MODE” button has been pushed. The ignition can be off or
on. The manual UP and DOWN arrow buttons will function with the EXCESS SLOPE light on, if the ignition is in “ON” or “ACC”
position. The “AIR”, “DUMP” AND “RAISE” buttons will not function if the EXCESS SLOPE light is on.

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MANUAL OPERATION
The UP and DOWN arrow button on the right side of the touch panel allow manual control of the air bags. The ignition must be
in the “ON” or “ACC” position and the park brake must be set for the UP and DOWN arrows to function. There are four sets of
buttons, front, left side, right side and rear. The UP arrow buttons will open the raise valves to allow are into the air bags,
raising the vehicle. The DOWN arrow buttons will open the lower valves to exhaust air from the air bags, lowering the vehicle.
These buttons will always operate two corners of the vehicle at a time for Bi-Axis leveling, both front air bags, both rear air
bags, the left front and left rear air bags or the right front and right rear air bags. It is not recommended to push more than
one UP or DOWN arrow at a time.
You can lower the vehicle first like the automatic leveling sequence does or you can level the vehicle by first lowering the side
and/or end of the vehicle opposite of any lit yellow level light. I. E. The left side level light is on. Push and hold the DOWN
arrow button for the right side. If lowering the right side does not turn the left side level light out, push and hold the left side UP
arrow to raise the left side of the vehicle. It is recommended to level the vehicle side to side first, if needed, then front to rear.
The UP and DOWN arrow buttons will not function if the LEVELING SYSTEM ACTIVE light is flashing.
NOTE: There is no EXCESS SLOPE or SLEEP mode in manual leveling. If the “AIR” button is pushed after manually
leveling the vehicle, even if all yellow level lights are out, the auto level sequence will start from the beginning
including first dumping all air from the air bags.
“DUMP” AND “RAISE” BUTTONS
The DUMP button will exhaust air from all of the suspension air bags to lower the whole vehicle. The RAISE button will add air
to all of the suspension air bags to RAISE vehicle. The ignition has to be in the “ON” or “ACC” position for the DUMP and
RAISE buttons to function but the park brake does NOT have to be set. The system has a wire that connects to the
transmission speed switch. When below the speed setting of the switch, the DUMP and RAISE buttons will latch in and lower
or raise the vehicle to the minimum (lower) or maximum (raise) height allowed by the suspension and air bags. If the system is
not connected to the speed switch, the buttons become momentary and will stop lowering or raising the vehicle when
released. If the park brake is off, the suspension will return to the normal ride height.
IMPORTANT: The DUMP and RAISE buttons are a feature that allow you to raise or lower the vehicle while moving at
a very slow speed to clear an obstacle such as a curb or branch. The vehicle should not travel any significant
distance without being at the proper ride height.

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PART 2 –TROUBLE SHOOTING
TROUBLE SHOOTING BASICS (Please read before continuing)
When trouble shooting the 700 series air leveling system, it is best to run the system in the manual mode to check individual
functions before operating the system in the automatic mode. If the system won’t work in manual, it won’t work in automatic.
It is important to remember the HWH works with the vehicle suspension to achieve leveling or ride height. Each HWH
air manifold has 6 valves, a right and left travel valve, a right and a left lower valve and a right and a left raise valve.
There is a manifold for the front axle and the rear axle. A travel valve allows air to pass through the manifold from a
Height Control Valve to the air bag so the Height Control Valves can control the suspension. A lower valve allows air
to exhaust from the air bag to lower the vehicle. A raise valve allows air to flow into the air bag to raise the vehicle.
How high of low a vehicle can go is a function of available air pressure and the limitations of the suspension
equipment, air bags, shocks, etc.
Start the engine and push the “TRAVEL MODE” button. Let air pressure build and allow the vehicle to return to travel height.
This will make the following procedures easier to perform. If the vehicle will not return to travel height, see Step 2.
When trouble shooting, it is important to pay attention to the air bags instead of just watching the vehicle. Because air
is highly compressible, watching the vehicle move up or down can give you a false impression of what is really happening.
When checking to see if a lower valve is working, wait until air stops exhausting then check that the air bags corresponding to
the DOWN arrow button being pushed are totally empty or flat. When checking to see if a raise or travel valve is working,
make sure there is adequate air supply and check the air bags corresponding to the UP arrow being pushed or if working on
the TRAVEL MODE, all the air bags should have re-inflated. This is the most reliable way to make sure the system is
functioning properly. It is best to check all four sets of UP and DOWN arrows. First use the DOWN arrow and check the
appropriate bags are empty then push the corresponding UP arrow and make sure the bags have re-inflated.
Each air manifold is equipped with two 20 psi pressure switches, one for each side. These are normally closed switches. The
contacts will open at approximately 20 psi. These switches are used as a warning device when traveling and also to establish
the high corner of the vehicle for automatic leveling. If the ignition is on and the park brake is off, one (1) minute after an air
bag pressure switch comes on, the green TRAVEL MODE light will go out and the master warning light will come on. The drive
axle manifold also has an 85 psi switch that monitors vehicle air system pressure. This switch is only used as a warning
device. If the ignition is on and the park brake is releasedthe TRAVEL MODE light will turn off and the master warning light
will turn on as soon as the switch comes on.
The air manifold MIOMs are equipped with LEDs that can assist with diagnostics. Refer to electrical diagrams for LED
information. Lit LEDs indicate there is an output but LOW VOLTAGE must always be considered and addressed. When
asked to check for +12 power or voltage and ground, ignition voltages should be above 10.5 volts and output
voltages should be above 10.0 volts. Equipment will work at a lower voltage but levels below 10.0 –10.5 volts may
indicate a connection, corrosion or battery issue. ALL VOLTAGES SHOULD BE CHECKED UNDER LOAD.
The trouble shooting steps start on the next page. The “Steps” are written in order of operation of the system. If
you are not familiar with the system, skipping steps can cause diagnostic issues. As you proceed through the
different Steps, it is assumed everything in previous Steps has been checked and is working as it should.
The “Steps” direct an operation and explain what should happen. Possible symptoms are listed in the “PROBLEM”
column. Diagnostics and repair solutions are in the “SOLUTION” column. Diagrams are in the “DIAGRAM” column
and also refer you to the corresponding diagram in the diagram section at the rear of this manual. These diagrams
will give you a complete view of the object you are dealing with.

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TROUBLE SHOOTING
Step 1. Check that the green TRAVEL MODE light is not on. Make sure the park brake is set. Turn the ignition to the “ON”
or “ACC” position. The TRAVEL MODE light should come on. +12 power for the touch panel and MIOMs is routed to the
front MIOM through the system latch in relay assembly.
PROBLEM SOLUTION DIAGRAMS
Step 1a. The
green TRAVEL
MODE light is
on with the
ignition off.
The issue will be at the front air module MIOM. There is
power on the red 6120 wire for pin A1 or the red 6102 wire for
pin D1 of the front MIOM main connector. There should be no
power on these wires with the ignition off. The 6120 wire is
ignition power. The 6102 wire is battery power. If there is
power on the 6120 wire there should also be power on the
6102 wire. If there is no power on the 6120 wire but there is
power on the 6102 wire, the CR1 or CR2 Bosch relay is stuck
on and should be replaced.
8 7 6 5 4 3 2 1 A
B
C
D
FRONT VIEW OF I/O MODULE
CONNECTOR
REFER TO MP84.3180
LINK LIGHT
PIN 1
HWH COMPUTERIZED LEVELING
WARNING!
UNDERSTAND OPERATOR'S MANUAL BEFORE USING. BLOCK FRAME AND TIRES
SECURELY BEFORE REMOVING TIRES OR CRAWLING UNDER VEHICLE.
EMERGENCY
STOP
MODE
TRAVEL
LEVEL
MODE
TRAVEL
RAISE
BRAKE
PARK/
SLOPE
EXCESS
NOT IN
DUMP
AIR
CN1
REFER TO MP84.6195
LINK LIGHT
REFER TO MP84.3180
SYSTEM LATCH
IN RELAYS
SEE MP84.3200
AB 61206101
REFER TO MP84.3060
Step 1b. The
green TRAVEL
MODE light is
off. The ignition
is on. The park
brake is set.
If a yellow level light is on, replace the touch panel. If a level
light is not lit, push the “RAISE” or “DUMP” button. If the light
above the button comes on, replace the touch panel. If the
light does not come on, there is a system power or
communication problem between the MIOMs and the touch
panel.
There is a link light on the back of the touch panel and one on
each air manifold MIOM. These lights should be flashing with
the ignition on. CHECK THAT ALL LINK LIGHTS ARE
FLASHING.
ALL LINK LIGHTS ARE FLASHING –Check for +12 power
on the red 6120 wire (pin A1) at the front MIOM. If +12 power
is present, replace the MIOM. If +12 power is not present,
there is an issue with the 6120 wire between the front MIOM
and the latch in relay assembly. Check the wire and plug
connections. Fix as necessary.
SOME LINK LIGHTS ARE OFF OR ON STEADY. There is
most likely a communication issue. There may also be a
power issue for a MIOM or the touch panel. Check for +12
power between wires 6122 (red) and 6230 white at the
MIOMs and touch panel. If +12 power is not present, repair
the harness wires as necessary.
If +12 power is present at all components, unplug the main
connector from the front and rear MIOMs and the 5 pin MTA
connector from the touch panel. At the touch panel, check
resistance between pins 1 and 2, the yellow and green wires,
of the MTA connector. There should be between 55 and 65
Ohms of resistance. If the resistance is not correct, there is an
issue with the harness
There is a 120 OHM resistor between the yellow and green
wires in the harness near the touch panel and the rear MIOM.
If you measure approximately 120ohms, one of the resistors
may be bad or possibly a bad spot in oneof the wires.
If resistance measures OK, make sure the yellow and green
wires are properly seated in the connectors. Make sure the
yellow and green wires are in the proper location at all
connectors including the front MIOM.
At the MIOMs, the yellow wire should be on pin A2. The green
wire should be on pin B2. At the touch panel, the yellow wire
should be on pin 1 and the green wire should be on pin 2.
If resistance is OK and the wires are seated properly in the
correct locations, the issue is the touch panel or one of the
MIOMs. There is no good way to test these components. Try
the touch panel first but you may want to order all three parts
and make arrangements to return the unused parts.
8 7 6 5 4 3 2 1 A
B
C
D
FRONT VIEW OF I/O MODULE
CONNECTOR
REFER TO MP84.3180

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TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
REFER TO MP84.3181
Step 1b. Cont. ALL LINK LIGHTS ARE OFF –Make sure there is a good
ground on the MIOM ground stud. Fix if necessary. With the
ignition on, check at the main connector of the front MIOM for
+12 power between the red 6102 wire (pin D1) and the white
6230 wire (pin D3).
There is +12 power between the red 6102 wire (Pin D1)
and the white 6230 wire (pin D3) in the front MIOM main
connector. Check for power between the red 6122 wire (pin
B1) and the white 6230 wire. If power is present, refer to
“SOME LINK LIGHTS ARE OFF OR ON STEADY” on the
preceding page. If power is not present, replace the MIOM.
There is no +12 power between the red 6102 wire (Pin D1)
and the white 6230 wire (pin D3) in the front MIOM main
connector. Check for power between the 6230 ground wire
and the red 6120 wire in pin A1.
There is +12 power on the red 6120 wire at the front MIOM
main connector, pin A1 but no power on the red 6102
wire, pin D1. The issue is the CR1 relay in the latch in
assembly or the battery supply wire, 6102. Check for ground
on the white 6235 wire at terminal 86 of CR1 and check for
+12 on the red 6120 wire at terminal 85 of CR1. If ground is
not present, check the 6235 wire and its connections to the 2-
pin MIOM Packard connector for the latch in assembly. Fix as
necessary. If the wire and connections are good, replace the
MIOM. If +12 power is not present at terminal 85, the issue is
with the 6120 wire at the latch in assembly. Fix as necessary.
If there is power and ground for the CR1 relay coil, check for
+12 power on the red 6101 wire for terminal 30 of CR1. If
power is present at terminal 30 of CR1, check for power on
the red 6102 wire for terminal 87 of CR1. If power is not
present, replace the CR1 relay. If power is present at terminal
87, there is an issue with the red 6102 wire, pin connections
or connections between the latch in assembly and the front
MIOM. Fix as necessary. If power is not present at terminal
30 of CR1, the issue is the red 6101 wire from the reset
switch to CR1, terminal 30, the reset switch, the red 6100 wire
from the reset switch to its source or the fuse for the 6100
wire is blown. If the fuse is ok, repair the wire, switch or
connections as necessary.
62356101
6102
6101 6235
6102 7500
6235
6120
61027500
6120
B A
CR1 CR2
87 85
8630
8587
30 86
REFER TO MP84.3200

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 11 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
6101
6102
CR2
B A
RESET SWITCH (NC)
61006101
6101 6101 6100
FUSE
5 AMP
TO +12 BATTERY
87 85
8630
REFER TO MP84.3200
Step 1b. Cont. The five amp fuse for +12 battery power to the latch in
relay assembly is blown. Turn the ignition off. Replace the
fuse. If the fuse blows, the problem is on the red 6100 or red
6101 wire between the latch in relay assembly and the fuse. If
the fuse does not blow, unplug the front MIOM. Turn the
ignition key on. If the fuse blows, the issue is on the red 6102
between the relay assembly and the front MIOM. If the fuse
does not blow, turn the ignition off. Unplug the rear MIOM,
both touch panel plugs and the level sensing unit. Leave the
front MIOM unplugged. There should be no continuity
between the red wires for pins B1, C1, D1 of the front MIOM
main connector and any white wires in the main harness or to
any frame ground. Check for continuity and fix as necessary.
If the harness wires are ok, turn the ignition on and plug the
front MIOM back in. If the fuse blows, replace the MIOM. If the
fuse does not blow, plug in the rear MIOM. If the fuse blows,
replace the rear MIOM. If the fuse does not blow, plug in the
5-pin MTA touch panel connector. If the fuse blows, replace
the touch panel. If the fuse does not blow, plug the 6-pin UML
touch panel connector back in. If the fuse blows, there is a
problem with the red 6110 wire in the warning light pigtail.
Repair as necessary. If the fuse does not blow, plug the level
sensing unit back in. If the fuse blows, replace the sensing
unit. If the fuse does not blow, continue with system
diagnostics as needed. TRUNK
HARNESS
HWH MAIN
HWH MAIN
HARNESS
TRUNK
RESISTOR
TERMINATING
DO NOT CUT TERMINATING
RESISTOR
DO NOT CUT
TOUCH PANEL
SEE MP84.6195
MASTER
WARNING
LIGHT
7699
6110
LATCH
SYSTEM
LEVEL SENSING UNIT
SEE MP84.3433
AB
FRONT AIR MANIFOLD
I/O MODULE
SEE MP84.3180
SEE MP84.3190
I/O MODULE
REAR AIR MANIFOLD
HWHCOMPUTERIZEDLEVELING
WARNING!
UNDERSTANDOPERATOR'SMANUAL BEFORE USING. BLOCK FRAME AND TIRES
CANCEL
MODE
TRAVEL
LEVEL
MODE
TRAVEL
RAISE
BRAKE
PARK/
SLOPE
EXCESS
NOTIN
DUMP
AIR
SECURELYBEFOREREMOVINGTIRES OR CRAWLING UNDER VEHICLE.
REFER TO MP84.3060
WARNING: DO NOT CRAWL UNDER THE VEHICLE UNLESS THE VEHICLE IS SECURELY SUPPORTED AND
CANNOT DROP WHEN AIR IS EXHAUSTED FROM THE SUSPENSION AIR BAGS. MAKE SURE THERE IS AMPLE
ROOM UNDER THE VEHICLE TO AVOID MOVING SUSPENSION PARTS WHEN AIR IS EXHAUSTED OR ADDED TO
THE SUSPENSION AIR BAGS. SERIOUS INJURY OR DEATH CAN OCCUR
Step 2. Start the vehicle engine. Make sure there is at least 100 psi in the vehicle air tanks. Push the “TRAVEL MODE”
button. The blue TRAVEL MODE button light should flash a few times. The vehicle should come to ride height. Check that
all the suspension air bags are inflated.
Step 2a. The
blue Travel
Mode button
light does not
flash.
Review Part 1b. Make sure there is good +12 power and
ground to the MIOMs and touch panel and make sure all link
lights are flashing as explained in Step1b. If Step 1b. checks
ok, replace the touch panel. LEFT FRONT TRAVEL
RIGHT FRONT TRAVEL
REFER TO MP84.3180
OR MP84.3190
Step 2b. One or
more air bags
are not inflated.
The blue Travel
Mode button
light did flash
If there is a Height Control Valve for each side of the axle, the
issue could be HWH or the Height control valve.
WARNING: MAKE SURE THE FRAME OF THE VEHICLE IS
PROPERLY SUPPORTED BEFORE CRAWLING UNDER
THE VEHICLE. SEVERE INJURY OR DEATH CAN OCCUR.
With the ignition on check that the travel valve LED for the
bag(s) not inflating is lit. There are two travel valves and travel
LEDs on each manifold. If the travel valve LED is lit, turn
the “BY-PASS VALVE” T-handle on the side of the manifold
counterclockwise several turns. If the bag inflates, the travel
valve for that bag is most likely the issue.
LEXHAUST R
I
VALVE
BY-PASS
[ HCV ]
BAG
AXLE AIR IN
VALVE
BY-PASS
REFER TO MP84.3181

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 12 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 2b. Cont. Check for +12 volts between the two pins of the MIOM
Packard connector. If power is present, replace the valve. If
power is not present, the issue is the connection or MIOM. If
the connection of the wires in the connector is ok, replace the
MIOM.
If the bag does not inflate with the manifold T-handle opened,
the issue is the Height control valve or possibly something in
the system plumbing. Make sure the T-handle is closed
snugly after completing the test.
NOTE: If the T-handle does not turn fairly easy, do not try to
force it, you can damage the manifold. Go ahead with the
voltage test at the valve and if voltage is ok, remove the travel
valve. If air comes out of the manifold, replace the valve. If no
air comes out, the issue is the Height Control Valve or the
plumbing.
If the travel valve LED is not lit, turn the ignition off, unplug
the valve, the main MIOM connector and the 2 pin MIOM plug
for high current and ground. Wait about 10 seconds, then plug
the main connector and the 2 pin connector back in. Do not
plug the valve back in. Turn the ignition on. If the travel valve
LED now comes on, replace that travel valve. If the travel
valve LED still does not come on, replace the MIOM.
W2700
TRAVEL
RS
B A
ABAB
B A
BA
AB
AB
TRAVEL
W1700
LS
RED (6100)
WHITE (6234)
6245
2700 1700 6246
WHITE
BLACK
MAIN
CONNECTOR
REFER TO MP84.3181
Step 3. With the ignition in the “ON” or “ACC” position and the park brake set, push the “DUMP” button to exhaust the air
from all the air bags. The DUMP light should start flashing and continue flashing. When air has stopped exhausting, push
the “CANCEL” button. The DUMP light should stop flashing. Check that all the air bags are totally deflated.
Step 3a. The
DUMP light will
not come on
and flash.
Whenever the ignition is in the “ON” or “ACC” position, there
should be +12 volts on the black 9900 wire going to the main
connector, pin C6, of the front MIOM. This is the speed switch
wire. If +12 is not present, there is an issue with the
transmission output, the 9900 wire, its connections to the
HWH MIOM or the transmission speed switch. If +12 is
present, replace the touch panel.
NOTE: +12 volts will not be present when the vehicle is
traveling above the speed the speed switch is
programmed for.
8 7 6 5 4 3 2 1 A
B
C
D
FRONT VIEW OF I/O MODULE
CONNECTOR
REFER TO MP84.3180
EXHAUST
AXLE AIR IN
[ HCV ]
L
E
F
T
BY-PASS
VALVE
R
I
G
H
T
AIR
IN
BAG
R
BAG
PSW
BY-PASS
VALVE
BAG
CHECK VALVES
AIR SUPPLY
AIR BAGS
LINE TO
CONTROL
HEIGHT
LINE FROM
VALVES
3.400"
FRONT AIR MANIFOLD
REAR VIEW
SWITCHES (2)
PRESSURE
PRESSURE REGULATOR
REFER TO MP74.2670A
Step 3b. One or
more air bags
do not deflate.
The other air
bags do deflate.
First, make sure the exhaust ports for the bags that will not
exhaust air are not plugged with dirt or debris. Clean if
necessary. Use caution as the air will start to dump after
cleaning the ports if the DUMP light is still flashing. With
the DUMP button light flashing, check the LED for any lower
valve that controls an air bag that did not exhaust air. If the
LED is lit, check for +12 volts between the two pins of the
MIOM connector. If +12 volts is present, replace the valve. If
+12 is not present the issue is the wires or their connections
in the plug. Fix if possible or replace the MIOM. If the LED is
not lit, turn the engine off, unplug the valve, the main MIOM
connector and the 2 pin MIOM plug for high current and
ground. Wait about 10 seconds, then plug the main connector
and the 2 pin connector back in. Do not plug the valve back
in. Turn the ignition on. If the lower valve LED now comes on,
replace that lower valve. If the lower valve LED still does not
come on, replace the MIOM.
*
RIGHT FRONT TRAVEL
RIGHT FRONT LOWER
RIGHT FRONT RAISE
AIR COMPRESSOR
LINK LIGHT
LEFT FRONT LOWER
LEFT FRONT TRAVEL
SYSTEM LATCH LEFT
FRONT
RAISE
REFER TO MP84.3180

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 13 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 3c. None of
the air bags will
deflate
Check that all exhaust ports are clear and not plugged with
dirt or debris. Clean if necessary. Use caution as the air will
start to dump after cleaning the ports if the DUMP light is
still flashing.
With the DUMP button light flashing, check the lower valve
LEDs. If any of the lower valve LEDs are lit, +12 power and
ground for the MIOM is present. Remember, low voltage
could be the issue. If no LEDs are lit, check for +12 volts on
the red 6100 wire and ground on the white 6230 wire in the 2
pin gray connector at the front and rear MIOMs. If +12 or
ground is not present, check all connections. If necessary,
trace the wires to their source. The red 6100 wire should have
a fuse. If the fuse is blown, there is most likely a problem with
the red 6100 wire in the harness. Fix any connection or wire
issues as necessary. If there is good voltage and ground to
the MIOMs, check the individual valves according to the
instructions in Part 3b.
W7500
RELAY
LATCH
AB
BA
SEE MP84.6085
SEE MP84.3180
INFORMATION
FOR CONNECTION
RED (6100)
WHITE (6234)
6244
2500
WHITE
BLACK
HIGH CURRENT
CONNECTOR
CONTROL
W9700
RELAY
COMP
REFER TO MP84.3181
OR MP84.3191
Step 4. With the engine running, ample air in the vehicle air tanks and all the air bags fully deflated, push and hold any UP
arrow button for about 10 seconds or until the vehicle starts to rise. If the “NOT IN PARK/BRAKE” touch panel light
comes on while pushing an UP arrow button, proceed to Step 7. Make sure the corresponding air bags are inflating.
Make sure no other air bags have inflated. After checking the air bags, push and hold the corresponding DOWN arrow
button until air stops exhausting. Make sure the corresponding air bags are fully deflated. Make sure the other air bags are
still fully deflated. Repeat this test with the other three sets of UP and DOWN arrow buttons. The order is not important.
Starting with the front, then rear, then left side and finally the right side would be a good order.
*
RIGHT FRONT TRAVEL
RIGHT FRONT LOWER
RIGHT FRONT RAISE
AIR COMPRESSOR
LINK LIGHT
LEFT FRONT LOWER
LEFT FRONT TRAVEL
SYSTEM LATCH LEFT
FRONT
RAISE
REFER TO MP84.3180
OR MP84.3190
CONTROL
W9700
RELAY
COMP
W2700
TRAVEL
RAISE
W2500
W2600
LOWER
RS
RS
RS
W7500
RELAY
LATCH
B A
ABAB
B A
BA
AB
AB
TRAVEL
W1700
LS
W1600
LOWER
LS
LS
RAISE
W1500
SEE MP84.6085
SEE MP84.3200
SEE MP84.3180
INFORMATION
FOR CONNECTION
RED (6100)
WHITE (6234) 6235
7500
6102
6120
6245
2700
6243
2600
6244
2500
1700
6246
1600
6241
1500
6242
WHITE
BLACK
HIGH CURRENT
CONNECTOR
REFER TO MP84.3181
OR MP84.3191
Step 4a. Neither
of the air bags
inflate
Some front air manifolds have a regulator on the air supply for
the manifold. This should normally be set at approximately 50
psi. Refer to MP44.3500 in the diagram section of this manual
for instructions on setting this regulator.
Check the raise valve LEDs on the MIOM(s) while pushing the
UP arrow. If either or both LEDs are on, the regulator may be
the issue. Check that there is +12 volts between the two pins
of the MIOM connectors for the valves. If LEDs are lit with no
voltage at the connectors, there could be an issue with the
wires or pin connections. If these are good, replace the
MIOM. If voltage is present at the connectors, make sure
there is air going through the regulator. Remove the pipe plug
from the regulator port where the pressure gauge would
install. If no air comes out, the regulator is the issue. If air
does come out of the port, replace the raise valves.
If either or both raise valve LEDs are off, turn the engine off,
unplug the valve for any raise LED not lit. Unplug the main
MIOM plug and the 2 pin MIOM plug for high current and
ground. Wait about ten seconds then plug the main plug and
high current plug back in. Do not plug the valve(s) back in.
Start the engine. Push the UP arrow and check the LEDs. If
the LED now comes on, replace that raise valve. If the LED
still does not come on, replace the MIOM.
R
200
BAG
AIR
IN
1/8 INCH
PLUG
REGULATOR
KNOB
ADJUSTMENT
UNLOCK
LOCK
REFER TO MP44.3500

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 14 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 4b. One
bag inflates, the
other does not.
While pushing the UP arrow button, check the raise valve
LED for the bag that will not inflate. If the LED is off, turn the
engine off, unplug that raise valve, unplug the main MIOM
plug and unplug the 2 pin MIOM plug for high current and
ground. Wait about ten seconds then plug the main plug and
high current plug back in. Do not plug the valve back in. Start
the engine. Push the UP arrow and check the LEDs. If the
LED now comes on, replace that raise valve. If the LED still
does not come on, replace the MIOM.
If the raise valve LED is on, check for +12 volts between the
two pins of the MIOM raise valve plug. If voltage is present,
replace that raise valve. If voltage is not present. There may
be an issue with the wires or pin connections. If these items
are ok, replace the MIOM.
REFER TO MP84.3180
OR MP84.3190
CONTROL
W9700
RELAY
COMP
W2700
TRAVEL
RAISE
W2500
W2600
LOWER
RS
RS
RS
W7500
RELAY
LATCH
B A
ABAB
B A
BA
AB
AB
TRAVEL
W1700
LS
W1600
LOWER
LS
LS
RAISE
W1500
SEE MP84.6085
SEE MP84.3200
RED (6100)
WHITE (6234) 6235
7500
6102
6120
6245
2700
6243
2600
6244
2500
1700
6246
1600
6241
1500
6242
WHITE
BLACK
HIGH CURRENT
CONNECTOR
REFER TO MP84.3181
OR MP84.3182
Step 4c. The
correct air bags
do not inflate
(or deflate)
This will only show up when doing a side raise or lower. The
issue would be incorrect plumbing or valves not plugged in
correctly. The two front air valve connections or bag plumbing
connections could be swapped or the same could happen at
the rear manifold. A front and rear swap would be very
unlikely.
REFER TO MP74.0010
OR MP84.3181
OR MP84.3191
Step 4d. The air
bags inflate but
the vehicle will
not rise.
If the front will not raise, check the front air manifold. Some
front air manifolds have a regulator on the air supply for the
manifold. This should normally be set at approximately 50 psi.
Refer to MP44.3500 in the diagram section of this manual for
instructions on setting this regulator.
For the sides or rear of the vehicle or if the front manifold
does not have a regulator, the issue will be with the vehicle air
supply or suspension components. All the HWH manifolds
can do is let air into the air bags. How high the vehicle raises
is a function of available air pressure and supply.
L
E
F
T
R
I
G
H
T
AIR
IN
BAG
R
BAG
PSW
CHECK VALVES
AIR SUPPLY
SWITCHES (2)
PRESSURE
PRESSURE REGULATOR
REFER TO MP74.2670A
Step 4e. A bag
not controlled
by the UP arrow
being pushed
has inflated
This is a highly unlikely situation but if it occurs, the issue
would be with the MIOM. Replace the MIOM that controls the
air bag that should not inflate. It will not be a stuck valve. If a
raise or travel valve was stuck open, the air bag would never
stay deflated.
Step 4f. A bag
will not deflate. This should have been checked when the “DUMP” button was
pushed. Make sure the exhaust port is not plugged. If while
pushing the DOWN arrow button, that lower valve LED comes
on, check for +12 volts between the two pins of the MIOM
connector for that lower valve. If voltage is present, replace
the valve. If voltage is not present, make sure the wires and
pin connections are good. If not, fix if possible. If the wires
and connection are good, replace the MIOM. If the lower
valve LED does not come on, turn the ignition off, unplug that
valve, unplug the MIOM main connector and unplug the
MIOM 2 pin high current connector. Wait about 10 seconds
then plug the main connector and the high current MIOM
connector in. Do not plug the valve in. Turn the ignition on.
Push the DOWN arrow button for that lower valve. If the LED
now comes on, replace that valve. If the LED does not come
on, replace the MIOM.
REFER TO MP84.3180
OR MP84.3190
CONTROL
W9700
RELAY
COMP
W2700
TRAVEL
RAISE
W2500
W2600
LOWER
RS
RS
RS
W7500
RELAY
LATCH
B A
ABAB
B A
BA
AB
AB
TRAVEL
W1700
LS
W1600
LOWER
LS
LS
RAISE
W1500
SEE MP84.6085
SEE MP84.3200
RED (6100)
WHITE (6234) 6235
7500
6102
6120
6245
2700
6243
2600
6244
2500
1700
6246
1600
6241
1500
6242
WHITE
BLACK
HIGH CURRENT
CONNECTOR
REFER TO MP84.3181
OR MP84.3182

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 15 of 39
TROUBLE SHOOTING
Step 5. COMPRESSOR CHECK -The system is equipped with an auxiliary 12 volt compressor. The compressor is used
to supplement the vehicle air supply when the vehicle engine is off and the system is in the sleep mode. The compressor is
turned on anytime the system is in an automatic leveling sequence, including the SLEEP mode, once the system is in the
raise mode. Also the compressor is turned on anytime any UP arrow button or the “RAISE” button is being pushed. Turn
the ignition to “ON” or “ACC” and push any UP arrow button, the compressor should run.
PROBLEM SOLUTION DIAGRAMS
*
RIGHT FRONT TRAVEL
RIGHT FRONT LOWER
RIGHT FRONT RAISE
AIR COMPRESSOR
LINK LIGHT
LEFT FRONT LOWER
LEFT FRONT TRAVEL
SYSTEM LATCH LEFT
FRONT
RAISE
REFER TO MP84.3180
CONTROL
W9700
RELAY
COMP
W7500
RELAY
LATCH
BAB
B A
BA
A
SEE MP84.6085
SEE MP84.3200
SEE MP84.3180
INFORMATION
FOR CONNECTION
RED (6100)
WHITE (6234)
6235
7500
6102
6120
2600
6244
2500
WHITE
BLACK
HIGH CURRENT
CONNECTOR
REFER TO MP84.3181
Step 5a. The
compressor will
not run when an
UP arrow button
is pushed.
Check the LED for the compressor output on the front air
manifold module. The LED should be lit while pushing the UP
arrow.
If the compressor LED does NOT comes on while
pushing an UP arrow, turn the ignition off and unplug the
compressor control wire, 9700, at the module. Unplug the
main module connector and the 2 pin high current module
connector. Wait about 10 seconds then plug the main module
connector and the 2 pin high current connector back in. Do
not plug the compressor wire back in. Push an UP arrow and
check the compressor LED. If the LED does not come on,
replace the module. If the LED now comes on, the issue is the
9700 wire or at the compressor.
Unplug the 9700 wire at the compressor. Plug the 9700 wire
back in at the module. Push any UP arrow button and check
the compressor LED. If the LED does not come on or comes
on briefly and goes out, the 9700 wire has a short to ground.
Fix as necessary. If the LED comes on, check the wiring at
the compressor relay to make sure there is not a bad spot in
the wire. If the wire is ok, replace the compressor relay.
If the compressor LED comes on while pushing an UP
arrow, the issue is the MIOM, the 9700 wire or a problem at
the compressor.
Note: Some early 700 series compressors were grounded
through the compressor mounting bracket. More recent
compressors will have a white ground wire with a Packard
connector. Either way, make sure there is a good ground for
the compressor. The ground for the motor, the relay and the
normally open water trap valve all go to the same bolt on the
water trap mounting bracket. If necessary, add a #10 ground
wire from the compressor bracket to a good frame ground.
While pressing an UP arrow, check for +12 volts on the 9700
wire at the MIOM. If voltage is not present, the issue is the
wire or the pin connections for the 9700 wire. If the wire and
connections are ok, replace the MIOM. Fix the wire or
connection if possible. If voltage is present at the MIOM,
check for voltage at the compressor relay, terminal 1. If
voltage is not present on the 9700 wire at terminal 1, there is
an issue with the 9700 wire or its connections. Fix as
necessary. If there is voltage on the 9700 wire at terminal 1,
check for +12 volts on the red battery supply wire attached to
terminal 3 of the compressor relay. If voltage is present on
terminals 1 (9700 wire) and 3 (red battery wire), while
pushing an UP arrow button, check for voltage on terminal 4.
Make sure the ground on terminal 2 of the relay is good. If
there is no voltage on terminal 4, replace the relay. If there is
voltage on terminal 4, replace the compressor.
BLACK ( GROUND )
RED +12
GROUND
WHITE
(GROUND)
(+12 SIGNAL)
15 AMP
+12 VOLT
BATTERY POWER
NORMALLY OPEN
12 VOLT AIR SOLENOID
12 VOLT
ESSEX
RELAY
COMPRESSOR HARNESS
FROM FRONT AIR
I/O MODULE
+12 SIGNAL - 9700
COMPRESSOR MOTOR FUSE
15 AMP
(A)
RELAY MTG. BOLT
6100
REFER TO MP84.6086

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 16 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 5a. Cont. If there is no voltage on terminal 3 (red battery wire),
check the fuse for this wire. On older systems the fuse is
close to the compressor. On later models, the fuse is close to
the source connection. If the fuse is good, the issue is the
wire, its connections or the source. Make sure the fuse is not
corroded and is making good contact with the fuse holder
terminals. If the fuse is blown, replace and push an UP arrow
button. If the compressor runs, continue with system
diagnostics. If the compressor still does not run, replace the
compressor
GROUND
WHITE
15 AMP
+12 VOLT
BATTERY POWER
12 VOLT
ESSEX
RELAY
FUSE
15 AMP
6100
REFER TO MP84.6086
Step 5b. The
compressor
runs but will not
build air
pressure.
Make sure the compressor intake filter is not blocked. The
water trap has a normally open valve at the bottom. This valve
will close whenever the compressor is running. If this valve
will not close, make sure the two wires for the valve are good
and making a good connection at the compressor relay. If the
wires and connections are good, replace the valve. Fix the
wires or connections as necessary or replace the valve if
necessary.
If there are no leaks at the compressor, connect a 200 psi
gauge directly to the compressor output before the regulator.
If the compressor produces at least 130-140 psi, the
compressor is ok. If not, replace the compressor. If the
compressor is ok, re-connect the line from the regulator and
connect the gauge to the main output after the regulator. If the
pressure is low, try to adjust the regulator to 110 psi. Replace
the regulator if necessary. If pressure is good after the
regulator, there is a leak somewhere else in the system.
Check all connections and lines in the system. Consult the
vehicle manufacturer for complete air connection diagrams.
NORMALLY OPEN AIR SOLENOID (1)
12 VOLT RELAY (2)
AIR FILTER
AIR LINE TO SUSPENSION
CHECK VALVE (3)
GRAY FROM
AIR SOLENOID
GROUND
FUSE
15 AMP
FLOW
GROUND TO RELAY MOUNTING BOLT
TO +12 BATTERY
POWER - 6100
REFER TO MP84.6085
Step 6. YELLOW LEVEL LIGHT CHECK –There are 4 yellow leveling lights on the right hand side of the touch panel. A
lit level light indicates that side or end of the vehicle is low. One or two level lights can be on at the same time. When all the
level lights are out, the vehicle should be level. Manually level the vehicle to the desired position. If any level lights are lit,
adjust the level sensing unit according to MP44.1511 (diagram section of this manual) so all level lights are off. Use the UP
and DOWN arrow buttons to raise and lower each side and end of the vehicle to make sure all four yellow level lights will
come on and go out.
Step 6a. No
touch panel
yellow level
lights will come
on.
Check if any of the LEDs on the level sensing unit are lit. If
any LED is lit, unplug the level sensing unit and apply a
ground to pin 1, 4, 5 and 6 of the harness plug. If the touch
panel level lights now come on, replace the sensing unit. If no
touch panel light will come on, make sure the harness wires
and connection are good, fix as necessary. If the wires and
connections are good, replace the MIOM. If no level sensing
unit LED is lit, unplug the sensing unit and check for +12
volts between pin 2 (white 6231 wire) and pin 3 (red 6121
wire) in the harness plug. If +12 is not present, make sure
the 6231 and 6121 wires and their connections to the plugs
are good. Fix as necessary. If the wires and connections are
good, replace the MIOM. If +12 is present, apply ground to
pin 1, 4, 5 and 6 of the harness plug. If the touch panel level
lights now come on, replace the sensing unit. If no touch
panel light will come on, make sure the harness wires and
connection are good, fix as necessary. If the wires and
connections are good, replace the MIOM.
1 2 3
654 SEE WIRE
LEGEND
BELOW
SEE
ELECTRICAL
CONNECTION
DIAGRAM
FRONT AIR
MANIFOLD
I/O MODULE
MP84.3180
SEE ELECTRICAL CONNECTION
DIAGRAM - HARNESS ROUTING
MOUNTING / ADJUSTMENT
SCREWS (3)
A
BD
C
YELLOW LEDS
BOTTOM VIEW OF
SENSING UNIT
LED A - FRONT OF VEHICLE
LED B - LEFT SIDE OF VEHICLE (DRIVER SIDE)
LED C - REAR OF VEHICLE
LED D - RIGHT SIDE OF VEHICLE (PASSENGER SIDE)
REFER TO MP84.3433

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 17 of 39
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 6b.
Opposing level
lights are on or
a touch panel
level light will
not go out.
Unplug the level sensing unit. If all touch panel level lights
go out, the issue is the sensing unit or a short in the harness.
Unplug the main front MIOM connector and make sure no
sensing unit wires are shorted together. If the harness is
good, replace the sensing unit. If the touch panel level
lights do not go out with the sensing unit unplugged, the
issue is the harness or the MIOM. Unplug the main front
MIOM connector and make sure no sensing unit wires are
shorted together. If the harness is good, replace the MIOM.
Step 6c. One or
more touch
panel level
lights will not
come on. Some
level lights do
come on.
Unplug the level sensing unit. Ground the four pins that
control the level lights. Make sure only one light comes on
and that it is the correct light.
Pin 1 –wire 0400 –Rear level light
Pin 4 –wire 0100 –Left side level light
Pin 5 –wire 0200 –Front level light
Pin 6 –wire 0300 –Right side level light
If the touch panel lights work properly, replace the sensing
unit. If the lights do not work properly, make sure the harness
wires and connections to the sensing unit and main MIOM
plug are good, fix as necessary. If the wires and connection
are ok, replace the MIOM.
If incorrect touch panel lights come on when grounding pins,
check the wire/pin locations. Most likely a harness is pinned
wrong.
SEE WIRE
LEGEND
BELOW
PIN 1 - BLACK - 0400 - SWITCHED GROUND WHEN REAR IS LOW
PIN 2 - WHITE - 6231 - GROUND FROM SENSING UNIT
PIN 3 - RED - 6121 - +12 VOLT FOR SENSING UNIT
PIN 4 - BLACK - 0100 - SWITCHED GROUND WHEN LEFT SIDE IS LOW
PIN 5 - BLACK - 0200 - SWITCHED GROUND WHEN FRONT IS LOW
PIN 6 - BLACK - 0300 - SWITCHED GROUND WHEN RIGHT SIDE IS LOW
SEE
ELECTRICAL
CONNECTION
DIAGRAM
FRONT AIR
MANIFOLD
I/O MODULE
MP84.3180
SEE ELECTRICAL CONNECTION
DIAGRAM - HARNESS ROUTING
MOUNTING / ADJUSTMENT
SCREWS (3)
A
BD
C
YELLOW LEDS
BOTTOM VIEW OF
SENSING UNIT
LED A - FRONT OF VEHICLE
LED B - LEFT SIDE OF VEHICLE (DRIVER SIDE)
LED C - REAR OF VEHICLE
LED D - RIGHT SIDE OF VEHICLE (PASSENGER SIDE)
WIRE LEGEND
1 2 3
654
REFER TO MP84.3433
Step 7. PARK BRAKE CHECK –If the park brake is not set, the touch panel “NOT IN PARK/BRAKE” light will come on
when pushing a manual UP or DOWN arrow button or the “AIR” button. The light will go out when the button is released
and the system will not perform the function for that button. The “NOT IN PARK/BRAKE” light will also come on if the
“RAISE” or “DUMP” buttons are pushed. These two functions will work without the park brake set.
IMPORTANT: Chock the wheels for the following tests and diagnostics.
Make sure the park brake is set and the ignition is in the “ON” or “ACC” position. Push any UP or DOWN arrow button. If
the “NOT IN PARK/BRAKE” light comes on, proceed to Step 7a. If the light does not come on, set the foot brake, release
the park brake and push any UP arrow button. The “NOT IN PARK/BRAKE” light should come on. Set the park brake and
push any UP arrow button. The “NOT IN PARK/BRAKE” light should not come on and the system should function.
Step 7a. The
NOT IN PARK
light comes on
with the park
brake set while
pushing an UP
arrow button.
With the park brake set, there should be a ground on the
black 9000 wire on pin D8 of the main MIOM plug.
If there is no ground on the wire, the issue is the black
9000 wire or its connection to the vehicle park brake switch.
Repair the wire as necessary or consult the vehicle
manufacturer for assistance with the park brake switch.
If there is a ground on the wire, make sure the wire is
properly seated in the plug. If the wire is ok, replace the
MIOM.
Step 7b. The
NOT IN PARK
light will not
come on while
pushing an UP
arrow button
with the park
brake released.
With the park brake released, there should not be a ground on
the black 9000 wire on pin D8 of the main MIOM plug.
If there is no ground on the wire, replace the MIOM.
If there is a ground on the 9000 wire, there is an issue with
the 9000 wire, it is attached directly to a ground or there is an
issue with the park brake switch. Trace the wire to its source
and repair as necessary. If the wire is attached directly to a
ground source, it must be moved to the park brake switch.
Contact the vehicle manufacturer for assistance.
8 7 6 5 4 3 2 1 A
B
C
D
FRONT VIEW OF I/O MODULE
CONNECTOR
REFER TO MP84.3180
OR MP84.3010

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 18 of 39
TROUBLE SHOOTING
Step 8. TEST FOR 20 PSI AIR BAG PRESSURE SWITCHES –Turn the ignition key to the “ON” or “ACC” position. Use
the “DUMP” button to exhaust all air from the all of the air bags. With the bags deflated, the air bag pressure switch
contacts should be closed. There should be a ground on the wire for each switch. Make sure there is a minimum of 110 psi
in the vehicle air tanks. Start the engine if necessary. Push the front UP arrow button for 2 or 3 seconds then the same with
the rear UP arrow button. The pressure switch wires should not have a ground present. If a switch still has a ground, add a
little more air to the air bag and check again.
Left front pressure switch –Pin D5 –black 1210 wire –Front MIOM
Right front pressure switch –Pin A6 –black 2210 wire –Front MIOM
Right rear pressure switch –Pin A6 –black 3210 wire –Rear MIOM
Left rear pressure switch –Pin D5 –black 4210 wire –Rear MIOM
Pressure switch ground –Pin D2 –white 6232 wire, Front MIOM and white 6233 wire Rear MIOM
Unplug the main MIOM plugs to check the switches. (You will have to plug the MIOMs back in to put air into the airbags.)
With the air bags deflated, check to make sure there is continuity between Pin D2 and the pressure switch wires. After
adding air to the air bags, again, check between Pin D2 and the pressure switch wires. There should be no continuity.
PROBLEM SOLUTION DIAGRAMS
Step 8a. With
the air bags
deflated, there
is no continuity
between Pin D2
and the
pressure switch
wire.
If there is no continuity, unplug the pressure switch and check
for continuity between the 2 pins in the pressure switch plug.
If there is no continuity, replace the switch. If there is
continuity, there is an issue with the harness wire or plug
connections. Fix as necessary.
Step 8b. With
the air bags
inflated, there is
continuity
between Pin D2
and the
pressure switch
wire.
If there is continuity, unplug the pressure switch and check for
continuity between the 2 pins in the pressure switch plug. If
there is continuity, replace the switch. If there is no continuity,
there is an issue with the harness wire or plug connections.
Fix as necessary.
RIGHT SIDE
VIEW
VALVE NOT SHOWN)
RIGHT TRAVEL
SOLENOID VALVE (LEFT
VALVE NOT SHOWN)
RIGHT LOWER
SOLENOID VALVE (LEFT
RAISE
RS
LOWER
RS RS
TRAVEL
LS
TRAVEL
LOWER
LS
RAISE
LS
PSW
LS
PSW
RS
AAB B A B A B B A B A B BA A
NASON
MODELSM
REFER TO MP74.2670A
OR MP742680A
Step 9. TEST FOR 85 PSI SYSTEM PRESSURE SWITCH –The 85 psi system pressure switch is on the rear air
manifold. This is used as a low air pressure warning device only. With low system air pressure, the ignition on and park
brake off, the master warning light will be on and the green TRAVEL MODE light will be off. It will not interfere with any
leveling operation, manual or automatic or with the “DUMP” or “RAISE” buttons. With system air pressure below 85 psi,
there should be a ground on the black 3215 wire. With system air pressure above 85 psi there should be no ground on the
black 3215 wire on Pin B8 of the rear air manifold. The ground is the white 6233 wire on Pin D2.
Chock the vehicle wheels. Pump the main brake several times or until the system pressure gauges are below 85 psi. Turn
the ignition on, apply the foot brake and release the park brake. Make sure the TRAVEL MODE light is off and the master
warning light is on. Set the park brake, start the engine and build system pressure to at least 110 psi. Set the foot brake
and release the park brake. Make sure the master warning light is off and TRAVEL MODE light is on.
Note: Make sure the air bags are inflated. Low air bag pressure will also turn the master warning light on and the TRAVEL
MODE light off.
Step 9a. With
low air
pressure, the
TRAVEL MODE
light remains on
and the master
warning light
remains off.
Unplug the system air pressure switch. There should be
continuity between the two pins of the switch plug. If there is
no continuity, replace the pressure switch. If there is
continuity, the issue is the wires, connections or the MIOM.
There is a short pigtail between the MIOM plug and the
pressure switch. Make sure wires are properly seated and the
connections are good. Fix as necessary. If wires and
connections are ok, replace the MIOM.
REFER TO MP74.2680A
Step 9b. With
110 psi or
greater in the
system air
tanks, the
ignition on and
the park brake
off, the master
warning light is
on and the
TRAVEL MODE
light is off.
Unplug the system air pressure switch. There should be no
continuity between the two pins of the switch plug. If there is
continuity, replace the pressure switch. If there is no
continuity, the issue is the wires, connections or the MIOM.
There is a short pigtail between the MIOM plug and the
pressure switch. Make sure wires are properly seated and the
connections are good. Fix as necessary. If wires and
connections are ok, replace the MIOM.
B A
SEE MP84.3190
I/O MODULE
REAR AIR MANIFOLD
SYSTEM
PRESSURE
SWITCH
ABB A
SWITCH
RIGHT REAR
PRESSURE LEFT REAR PRESSURE
SWITCH
6233 6233
32154210
6233 3210
REFER TO MP84.3060
OR MP74.2680A

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 19 of 39
TROUBLE SHOOTING
Step 10. MASTER WARNING LIGHT –The master warning light will come on if the system is in the auto level mode or if
using the manual UP and Down arrows, the “DUMP” button or “RAISE” button and the ignition is on. The master warning
light will also come on if the park brake is off and the ignition is on when there is low air bag pressure or system pressure.
The green TRAVEL MODE light should be off any time the master warning light is on.
PROBLEM SOLUTION DIAGRAMS
Step 10a. The
master warning
light will not
come on. Travel
Mode light is
working.
Power and control for the master warning light comes from
the 6 pin UML connector on the back or the touch panel. The
red 6110 wire from pin 2 is +12 volt supply. The control wire is
switched ground on the black 7699 wire from pin 5. The +12
volt power supply should be present anytime the ignition is on.
Push and hold an UP or Down arrow button to test the control
output. If either +12 or the switched ground is not present,
replace the touch panel. If both are present, the issue is the
wire, connection or the light itself.
LINK LIGHT
PIN 4 PIN 1
PIN 6
CN2 PIN 3
6110 7699
REFER TO MP84.6195
Step 11. “RAISE” BUTTON TEST –At this time, it is assumed the system functions properly in the manual leveling mode
using the UP and DOWN arrow buttons. It is also assumed the “DUMP” button is functioning properly which checks the
speed switch signal. Start the engine and make sure there is ample air supply, 110+ psi. Push the “DUMP” button to
exhaust all air from the air bags. Make sure all air bags are totally deflated. Push the “CANCEL” button. DO NOT USE THE
“TRAVEL MODE’ BUTTON. Push the “RAISE” button. The light above the “RAISE” button should start flashing and all air
bags should start to inflate and raise the vehicle.
Step 11a. The
light above the
“RAISE” button
does not flash.
Whenever the ignition is in the “ON” or “ACC” position, there
should be +12 volts on the black 9900 wire going to the main
connector of the front MIOM. (Pin C6) This is the speed
switch wire.
If +12 is not present, there is an issue with the transmission
output, the 9900 wire, its connections to the HWH MIOM or
the transmission speed switch.
If +12 is present, replace the touch panel.
Step 11b. The
air bags will not
inflate. The light
does flash.
Review Step 4. This checks the UP and DOWN arrow
buttons. If the four sets of UP and DOWN arrow button are
functioning properly, replace the touch panel.
AB
I/O MODULE
SEE MP84.3180
62357500 9700
TO +12 BATTERY
GROUND
PARK BRAKE
SPEED SW
MASTER
WARNING
LIGHT
6230 9000 9900
LATCH
SYSTEM
RESET
SWITCH 6101
6100
REFER TO MP84.3060
OR MP84.3180
Trouble shooting for automatic operation is started on the next page. At this time, it will be assumed that the
system is functioning properly with the manual UP and DOWN arrow buttons. It is also assumed the air bag
pressure switches are functioning properly. These switches are essential to the proper operation of the automatic
leveling sequence. If at anytime, issues are encountered, review Steps 1 through 10. The system must function
properly with the manual buttons or automatic leveling cannot function properly.

C:\TEMP\ml59101.doc | Revised: 20JUN18 | Page 20 of 39
AUTOMATIC DIAGNOSTICS
Step 12. For a detailed explanation of the automatic leveling sequence, see “AUTOMATIC OPERATION” in PART 1
of this manual. Make sure the park brake is set. Start the engine and make sure the air tanks are full. Push the “AIR”
button. The blue SYSTEM ACTIVE light above the “AIR” button should flash. One or two yellow level lights may be on. The
system will exhaust air from all air bags lowering the vehicle, even if no yellow level lights are lit. If no level lights are on
after all air has been exhausted from the air bags, the system will go immediately into the SLEEP mode. When all air is
exhausted from the bags, if any yellow level lights are lit, the system will level the vehicle by raising the low side and/or end
of the vehicle. When all four level lights are out, the vehicle is level and the processor will go into the SLEEP mode. The
LEVELING SYSTEM ACTIVE light will now flash rapidly. The ignition key can now be turned off. The LEVELING SYSTEM
ACTIVE light will continue to flash rapidly.
NOTE: After the initial lowering procedure of automatic leveling, if any yellow level lights are lit, one lower valve and the
compressor are turned on and will remain on until leveling is achieved or the system goes to EXCESS SLOPE.
EXCESS SLOPE occurs if the system tries to level the vehicle for 15 minutes and a yellow level light remains on.
The SLEEP mode will continue with the LEVELING SYSTEM ACTIVE light flashing rapidly until the “CANCEL” button or
the “TRAVEL MODE” button is pushed with the ignition in “ON” or “ACC”. Releasing the park brake with the ignition on or
off will cancel the SLEEP mode and turn the LEVELING SYSTEM ACTIVE light off.
TROUBLE SHOOTING
PROBLEM SOLUTION DIAGRAMS
Step 12a. The
“NOT IN
PARK/BRAKE”
light comes on
while pushing
the “AIR”
button.
If the system is working with the manual UP and DOWN arrow
buttons, this is a near impossibility. Review Step 7.
Step 12b. The
LEVELING
SYSTEM
ACTIVE light
will not come
on.
Push any UP or DOWN arrow button. If the system functions
with a manual button, replace the touch panel. If the system is
not functioning in manual, start back with Step 1 and continue
until the system functions with the manual UP and DOWN
arrow buttons.
Step 12c. The
vehicle is not
level within
tolerances after
auto leveling
It is critical that the yellow leveling lights and the air bag
pressure switches are functioning properly. Review Step 6 to
check the level sensor and Step 8 to check the 20 psi air bag
pressure switches.
LATCH IN RELAY ASSEMBLY INFORMATION (FOR SLEEP MODE) -The ignition can be turned off after automatic
leveling is complete. The system should remain in the SLEEP mode. There is a relay assembly that is used to latch in
power to the MIOM and touch panel. This assembly is located within about 18” of the front air module.
The latch in relay assembly will be on any time the ignition is in the “ON” or “ACC” position. There are two relays in the
assembly labeled CR1 and CR2. Ignition and battery power are routed to the relay assembly. The battery power is routed
through a reset switch to the normally open contacts of CR1. The reset switch is a momentary, normally close switch and
should be close to the relay assembly. Main ignition power for the front MIOM and touch panel is routed to the front MIOM
main connector, pin A1, through this latch in assembly and is used to turn CR1 relay on. The CR1 relay supplies battery
power to the front MIOM main connector, pin D1, when the ignition is on.
There are four wires between the MIOM and latch assembly: red 6120, +12 ACC power, main connector, pin A1 and red
6102, +12 battery, main connector, pin D1. The black 7500, sw. +12 for CR2 control and the white 6235, ground for relays
are in a 2-pin Packard connector at the MIOM. Ground on the 6235 wire is constant. The 6120 +12 ACC wire and the 6102
+12 battery wire will have +12 volts whenever the ignition is on. The 7500 CR2 relay control wire will have +12 volts
anytime the ignition is on or with the ignition off if the leveling system is in the SLEEP mode.