Jeep Wrangler TJ 2003 User manual

TABLE OF CONTENTS
1.0 INTRODUCTION .........................................................1
1.1 SYSTEM COVERAGE ...............................................1
1.2 SIX-STEP TROUBLESHOOTING PROCEDURE ..........................1
2.0 IDENTIFICATION OF SYSTEM .............................................1
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION ......................1
3.1 TEVES MARK 20I SYSTEM DESCRIPTION..............................1
3.1.1 PEDAL FEEL/VEHICLE CHARACTERISTICS.....................2
3.1.2 SYSTEM COMPONENTS.....................................2
3.1.3 ABS AND BRAKE WARNING INDICATORS......................2
3.1.4 CONTROLLER ANTILOCK BRAKE (CAB) .......................2
3.1.5 HYDRAULIC CONTROL UNIT .................................3
3.1.6 RELAYS/SWITCHES.........................................3
3.1.7 SENSORS .................................................3
3.2 DIAGNOSTIC TROUBLE CODES ......................................4
3.2.1 SYSTEM INITIALIZATION ....................................4
3.2.2 DIAGNOSTIC MODE ........................................4
3.2.3 INTERMITTENT DIAGNOSTIC TROUBLE CODES ................4
3.3 AXLE LOCK........................................................4
3.3.1 GENERAL .................................................4
3.3.2 DESCRIPTION .............................................4
3.4 USING THE DRBIIIT.................................................5
3.5 DRBIIITERROR MESSAGES .........................................5
3.5.1 DRBIIITDOES NOT POWER UP (BLANK SCREEN) ..............5
3.5.2 DISPLAY IS NOT VISIBLE....................................5
4.0 DISCLAIMERS, SAFETY WARNINGS .......................................5
4.1 DISCLAIMERS......................................................5
4.2 SAFETY...........................................................6
4.2.1 TECHNICIAN SAFETY INFORMATION..........................6
4.2.2 VEHICLE PREPARATION FOR TESTING........................6
4.2.3 SERVICING SUB-ASSEMBLIES ...............................6
4.2.4 DRBIIITSAFETY INFORMATION ..............................6
4.3 WARNING .........................................................6
4.3.1 VEHICLE DAMAGE WARNINGS ...............................6
4.3.2 ROAD TESTING A COMPLAINT VEHICLE.......................7
4.4 DIAGNOSIS........................................................7
5.0 REQUIRED TOOLS AND EQUIPMENT ......................................7
6.0 GLOSSARY OF TERMS...................................................8
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES ............................9
BRAKES (CAB)
CAB POWER FEED CIRCUIT .............................................10
CONTROLLER FAILURE .................................................13
G-SWITCH NOT PROCESSABLE ..........................................15
LEFT FRONT SENSOR CIRCUIT FAILURE ..................................19
LEFT REAR SENSOR CIRCUIT FAILURE ...................................19
i

TABLE OF CONTENTS - Continued
RIGHT FRONT SENSOR CIRCUIT FAILURE.................................19
RIGHT REAR SENSOR CIRCUIT FAILURE ..................................19
LEFT FRONT SENSOR SIGNAL FAILURE...................................22
LEFT REAR SENSOR SIGNAL FAILURE ....................................22
RIGHT FRONT SENSOR SIGNAL FAILURE..................................22
RIGHT REAR SENSOR SIGNAL FAILURE...................................22
PUMP MOTOR NOT WORKING PROPERLY.................................25
SYSTEM OVER VOLTAGE................................................29
SYSTEM UNDER VOLTAGE ..............................................31
*ABS WARNING INDICATOR ALWAYS ON ..................................33
*ABS WARNING INDICATOR INOPERATIVE.................................35
*BRAKE LAMP SWITCH..................................................37
*FRONT AXLE LOCK INDICATOR REMAINS FLASHING.......................38
*NO RESPONSE FROM CONTROLLER ANTILOCK BRAKE ....................40
*REAR AXLE LOCK INDICATOR REMAINS FLASHING ........................42
*REAR AXLE LOCK INOPERATIVE.........................................45
VERIFICATION TESTS
VERIFICATION TESTS...................................................47
8.0 COMPONENT LOCATIONS...............................................49
8.1 CONTROLLER ANTILOCK BRAKE ....................................49
8.2 DATA LINK CONNECTOR ...........................................49
8.3 G-SWITCH........................................................49
8.4 FUSES & RELAYS .................................................50
8.5 WHEEL SPEED SENSORS ..........................................50
8.6 WHEEL SPEED SENSOR CONNECTORS..............................50
8.7 BRAKE SWITCHES ................................................51
8.7.1 PARKING BRAKE ..........................................51
8.7.2 BRAKE SWITCH ...........................................51
9.0 CONNECTOR PINOUTS .................................................53
AXLE LOCK SWITCH (OFF-ROAD PACKAGE) ...............................53
BRAKE LAMP SWITCH ..................................................53
CONTROLLER ANTILOCK BRAKE .........................................53
DATA LINK CONNECTOR ................................................54
FRONT LOCKER INDICATOR SWITCH (OFF-ROAD PACKAGE) ................54
FRONT LOCKER PUMP (OFF-ROAD PACKAGE) .............................54
G-SWITCH (LHD) .......................................................55
INSTRUMENT CLUSTER C1..............................................55
INSTRUMENT CLUSTER C2..............................................55
LEFT FRONT WHEEL SPEED SENSOR ....................................56
LEFT REAR WHEEL SPEED SENSOR......................................56
FRONT LOCKER RELAY (OFF-ROAD PACKAGE) ............................58
REAR LOCKER RELAY (OFF-ROAD PACKAGE)..............................58
REAR LOCKER INDICATOR SWITCH (OFF-ROAD PACKAGE)..................58
REAR LOCKER PUMP (OFF-ROAD PACKAGE) ..............................58
RIGHT FRONT WHEEL SPEED SENSOR ...................................59
RIGHT REAR WHEEL SPEED SENSOR ....................................59
ii

TABLE OF CONTENTS - Continued
10.0 SCHEMATIC DIAGRAMS.................................................61
10.1 TEVES MARK 20I CONTROLLER ANTILOCK BRAKE - ABS...............61
10.2 AXLE LOCK.......................................................62
iii

NOTES
iv

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions, and graphics
needed to diagnose the 2003 TJ Chassis system
problems: Teves Mark 20i Antilock Braking System
(ABS) and Axle Lock. The diagnostics in this man-
ual are based on the failure condition or symptom
being present at time of diagnosis.
Follow the recommendations below when choos-
ing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the CAB. If the DRBIIItdisplays a ‘‘No
Response’’ condition, you must diagnose that
first.
2. Read DTC’s (diagnostic trouble codes) with the
DRBIIIt.
3. If no DTC’s are present, identify the customer
complaint.
4. Once the DTC or customer complaint is identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All sche-
matics are in Section 10.0.
An asterisk (*) placed before the symptom de-
scription indicates a customer complaint.
When repairs are required, refer to the appropri-
ate service manual for the proper removal and
repair procedure.
Diagnostic procedures change every
year. New diagnostic systems may be added; carryover
systems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE DI-
AGNOSTIC TROUBLE CODE. It is recommended
that you review the entire manual to become familiar
with all new and changed diagnostic procedures.
After using this book, if you have any comments
or recommendations, please fill out the form at the
back of the book and mail it back to us.
1.1 SYSTEM COVERAGE
This diagnostic manual covers the Teves Mark
20i Antilock Braking System (ABS) found on the
Jeep Wrangler. Diagnosis of the Axle Lock is cov-
ered in this manual.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the antilock brake system is done in
six basic steps:
•verification of complaint
•verification of any related symptoms
•symptom analysis
•problem isolation
•repair of isolated problem
•verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
Vehicles equipped with the Teves Mark 20i an-
tilock brake system can be identified by the pres-
ence of the hydraulic control unit (HCU) located
under the hood near the power brake booster. Vehi-
cles equipped with Axle Lock can be identified by
the presence of the Axle Lock Switch located on the
lower center of the instrument panel.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 TEVES MARK 20I SYSTEM
DESCRIPTION
An electronic control module is used to monitor
wheel speeds and to modulate (control) hydraulic
pressure in each brake channel to prevent wheel
lock-up during braking.
During a non-ABS stop, the system functions as a
standard front/rear split configuration. The pri-
mary hydraulic system supplies brake fluid pres-
sure to the front brakes, and the secondary hydrau-
lic system supplies the rear brakes. A conventional
combination/proportioning valve is used.
During an ABS stop, the system still uses the
front/rear hydraulic split; however, the brakes sys-
tem pressure is further split into three control
channels. During ABS operation, the front wheels
are controlled independently and are on two sepa-
rate control channels. The rear wheels are con-
trolled together through one control channel. By
using a separate control channel for each front
wheel, more steering control is maintained during
maximum braking.
During an antilock stop, ‘‘wheel lock-up’’ does not
necessarily mean that the wheel has locked, it
means only that the wheel is turning slower than
the vehicle speed. This is called ‘‘wheel slip’’ and is
indicated as a percentage. 0% slip means that the
wheel is rolling free and 100% slip means that the
wheel is locked. The antilock system maintains an
average of approximately 20% wheel slip.
It is important to remember that the antilock
brake system does not shorten the vehicle stopping
distance under all driving conditions, but provides
improved control of the vehicle while stopping.
Vehicle stopping distance is still dependent on ve-
hicle speed, weight, tires, road surface, and other
factors.
1
GENERAL INFORMATION

3.1.1 PEDAL FEEL/VEHICLE
CHARACTERISTICS
There are several pedal feel/vehicle characteris-
tics that are considered normal for antilock braking
that may require further explanation.
When stopping conditions activate the antilock
brakes, the driver may feel some vibrations/
pulsations in the brake pedal and may hear the
solenoid valves clicking and the pump motor run-
ning. The vibrations/pulsations are caused by the
isolating, building and decaying of brake fluid pres-
sure within the brake lines. The ABS prevents
complete wheel lock-up, but some wheel slip is
required for the best braking performance. This slip
may result in some tire chirping, depending on the
road surface. This chirping should not be inter-
preted as total wheel lock-up. Total wheel lock-up
leaves black tire marks on dry pavement. Antilock
braking may leave some light marks.
At the end of an ABS stop, the ABS system may
not function below 5 Km/h (3 mph). There may be a
slight brake pedal drop anytime the ABS is deacti-
vated.
In case of braking on a bumpy surface, the ABS
module may detect wheel locking tendencies due to
wheel hop and cycle ABS. In that event the brake
pedal may pulsate with a perceived loss of deceler-
ation. ABS braking may also be activated at times
while on dry pavement with sand, gravel, or other
loose debris on the road.
It should be noted that the pulsating pedal feel
characteristic will not illuminate the brake warning
indicators or set a diagnostic trouble code that is
stored in the Controller Antilock Brake (CAB).
When investigating a hard pedal feel, inspect the
sensor and tone wheel teeth for chips/broken teeth,
damaged sensor pole tips, excessive runout of the
tone wheel, or excessive gap.
3.1.2 SYSTEM COMPONENTS
Antilock Brake System
•controller antilock brake (CAB)
•vacuum booster
•master cylinder (w/center valves)
•hydraulic control unit (HCU)
valve block assembly: 6 valve solenoids (3 inlet
valves, 3 outlet valves), 3
accumulators
•pump/motor assembly: 1 motor
2 pumps
•G (acceleration) switch
•1 proportioning valve
•4 wheel speed sensor/tone wheel assemblies
•ABS warning indicator
•fuses and wiring harness
•fluid reservoir (integral part of master cylinder
assembly)
3.1.3 ABS AND BRAKE WARNING
INDICATORS
The amber ABS warning indicator is located in
the instrument cluster. It is used to inform the
driver that the antilock function has been turned off
due to a system malfunction. On a TJ model the
warning indicator is controlled by the CAB and the
ABS relay. The CAB controls the indicator by di-
rectly grounding the ABS relay control circuit. The
ABS relay grounds the indicator circuit when it is
de-energized.
The red brake warning indicator is located in the
instrument cluster. It can be activated by applica-
tion of the parking brake, low brake fluid level or by
turning the ignition switch to the start position.
3.1.4 CONTROLLER ANTILOCK BRAKE
(CAB)
The controller antilock brake (CAB) is a
microprocessor-based device that monitors wheel
speeds and controls the antilock functions.
The primary functions of the CAB are:
•monitor wheel speeds
•detect wheel locking tendencies
•control fluid pressure modulation to the brakes
during antilock stop operation
•monitor the system for proper operation
•provide communication to the DRBIIItwhile in
diagnostic mode
•control the ABS relay
•store diagnostic information in non-volatile mem-
ory
The CAB continuously monitors the speed of each
wheel. When a wheel locking tendency is detected,
the CAB will command the appropriate valve in the
HCU to modulate brake fluid pressure to that
wheel. Brake pedal position is maintained during
an antilock stop by being a closed system with the
use of three accumulators. The CAB continues to
control pressure in individual hydraulic circuits
until a wheel locking tendency is no longer present.
The CAB turns on the pump/motor during an an-
tilock stop.
The antilock brake system is constantly moni-
tored by the CAB for proper operation. If the CAB
detects a system malfunction, it can disable the
antilock system and turn on the ABS warning
indicator. If the antilock function is disabled, the
system will revert to standard base brake system
operation.
2
GENERAL INFORMATION

The CAB inputs include the following:
•four wheel speed sensors
•brake lamp switch
•ignition switch
•battery voltage
•diagnostic communication
•G switch (acceleration switch)
The CAB outputs include the following:
•six valve/solenoid drivers
•pump/motor actuation
•ABS warning indicator control
•diagnostic communication
3.1.5 HYDRAULIC CONTROL UNIT
The hydraulic control unit (HCU) contains the
valve block assembly, three accumulators, and the
pump/motor assembly.
Valve Block Assembly: The valve block assem-
bly contains 6 valves with three inlet valves and
three outlet valves. The inlet valves are spring-
loaded in the open position and the outlet valves are
spring loaded in the closed position. During an
antilock stop, these valves are cycled to maintain
the proper slip ratio for each channel. If a wheel
locks, the inlet valve is closed to prevent any further
pressure increase. Then the outlet valve is opened
to release the pressure to the accumulators until
the wheel is no longer slipping. Once the wheel is no
longer slipping, the outlet valve is closed and the
inlet valve is opened to reapply pressure. If the
wheel is decelerating within its predetermined lim-
its (proper slip ratio), both valves will close to hold
the pressure constant.
Pump/Motor Assembly: The pump/motor as-
sembly provides the extra amount of fluid needed
during antilock braking. The pump is supplied fluid
that is released to the accumulators when the outlet
valve is opened during an antilock stop. The pump
is also used to drain the accumulator circuits after
the antilock stop is complete. The pump is operated
by an integral electric motor. This motor is con-
trolled by the CAB. The CAB turns on the motor
when an antilock stop is detected. The pump con-
tinues to run during the antilock stop and is turned
off approximately 3-5 seconds after the stop is
complete. The pump mechanism consists of two
opposing pistons operated by an eccentric cam. One
piston supplies the primary hydraulic circuit. The
opposing piston supplies the secondary hydraulic
circuit. In operation, one piston draws fluid from
the accumulators. The opposing piston pumps fluid
to the valve body solenoids. The CAB monitors the
pump/motor operation.
Accumulators: The accumulators provide tem-
porary fluid storage during an antilock stop and are
drained by the pump/motor.
3.1.6 RELAYS/SWITCHES
Relays: The ABS Relay is located in the power
distribution center (PDC). When the relay is de-
energized, it supplies a ground to turn on the ABS
warning indicator. The ABS relay is controlled by
the CAB. The CAB energizes the relay when it
receives an ignition input signal.
3.1.7 SENSORS
Wheel Speed Sensors and Tone Wheels: One
wheel speed sensor (WSS is located at each wheel
and sends a small AC signal to the Controller
Antilock Brake (CAB). This voltage is generated by
magnetic induction when a toothed sensor ring
(tone wheel) passes by a stationary magnetic sensor
(wheel speed sensor). The CAB converts the AC
signals into digital signals for each wheel.
The front wheel sensor is attached to a boss in the
steering knuckle. The tone wheel is an integral part
of the front axle shaft. The rear speed sensor is
mounted in the caliper adapter plate (rear disc only)
and the rear tone wheel is an integral part of the
rear rotor hub. The front wheel speed sensor air gap
is NOT adjustable. The correct front wheel speed
sensor air gap is from 0.40mm to 1.3mm (0.0169to
0.0519). Preferred rear sensor air gap for drum
brake systems is 1.1mm (0.0439).Acceptable air gap
range is 0.92mm to 1.275mm (0.0369to 0.0509). All
wheel speed sensors have a resistance between 900
and 1300 ohms.
Correct antilock system operation is dependent
on correct wheel speed signals from the wheel speed
sensors. The vehicle’s wheels and tires should all be
the same size and type. In addition, the tires should
be inflated to the recommended pressures for opti-
mum system operation. Variations in wheel and tire
size or significant variations in inflation pressure
can produce inaccurate wheel speed signals; how-
ever, the system will continue to function when
using the mini-spare. When driven over rough road
surfaces, the rear wheel speed sensor signals may
be erratic and cause a false trouble code.
G (Acceleration) Switch: The CAB monitors
the acceleration switch at all times. The switch
assembly contains three mercury switches that
monitor vehicle deceleration rates (G-force). Sud-
den, rapid changes in vehicle and wheel decelera-
tion rate trigger the switch, sending a signal to the
CAB. The switch assembly responds to three decel-
eration rates; two for forward braking and one for
rearward braking.
3
GENERAL INFORMATION

3.2 DIAGNOSTIC TROUBLE CODES
The Teves Mark 20iAntilock Brake System (ABS)
module may report any of the following diagnostic
trouble codes:
•Controller Failure
•G Switch Not Processable
•Left Front Sensor Circuit Failure
•Left Front Sensor Signal Failure
•Left Rear Sensor Circuit Failure
•Left Rear Sensor Signal Failure
•CAB Power Feed Circuit
•System Over voltage
•System Under voltage
•Pump Motor Not Working Properly
•Right Front Sensor Circuit Failure
•Right Front Sensor Signal Failure
•Right Rear Sensor Circuit Failure
•Right Rear Sensor Signal Failure
Diagnostic trouble codes are retained in memory
until erased using the DRBIIIt, or automatically
erased after 255 key cycles.
3.2.1 SYSTEM INITIALIZATION
System initialization starts when the key is
turned to RUN. At this point, the CAB performs a
complete self-check of all electrical components in
the antilock brake systems.
At around 19 km/h (12 miles per hour), the pump
motor is briefly activated to ensure operation, and
wheel speed sensor circuitry is checked. If the brake
pedal is applied when the vehicle reaches 19 km/h
(12 mph), this check will be delayed until 40 km/h
(25 mph). If, during the dynamic test, the brake
pedal is applied, the driver may feel the test
through brake pedal pulsations. This is a normal
condition. Throughout the remainder of the drive
cycle, ongoing tests are performed, and the CAB
monitors ABS circuits for continuity.
If any component causes a diagnostic trouble code
during system initialization or dynamic check, the
CAB will illuminate the ABS warning indicator.
3.2.2 DIAGNOSTIC MODE
To enter diagnostic mode, vehicle speed must be
below 10 km/h (6 mph), a ‘‘no response’’ message
will be displayed by the DRBIIIt. The following are
characteristics of diagnostic mode:
•The ABS warning indicator will flash. If a hard
diagnostic trouble code is present, such as a
Speed Sensor Circuit or Signal Failure trouble
code or CAB Power Feed Circuit diagnostic trou-
ble code, the indicator will be illuminated without
blinking and limited diagnostic operations only
will be available until the diagnostic trouble code
condition is corrected.
•Antilock operation is disabled.
3.2.3 INTERMITTENT DIAGNOSTIC
TROUBLE CODES
If the malfunction is not present while perform-
ing a test procedure, the diagnostic procedures will
not locate the problem. In this case, the code can
only suggest an area to inspect. Check for the
following:
•loose or corroded connections
•damaged components (sensors, tone wheels espe-
cially)
•damaged wiring
•excessive axle shaft runout
•brake system hydraulic leaks
•base brake system problems, non-ABS related.
If no obvious problems are found, erase diagnostic
trouble codes and, with the key on, wiggle the wire
harness and connectors. Recheck for codes periodi-
cally as you work through the system. This proce-
dure may uncover an intermittent or difficult to
locate malfunction.
3.3 AXLE LOCK
3.3.1 GENERAL
For this vehicle, the Axle Lock has no dedicated
module controller. A manual switch located on the
instrument panel controls the system. No DTC’s
will occur for this system.
3.3.2 DESCRIPTION
The axle lock has the ability to lock the front and
rear axle differentials. The system components are
the instrument cluster, axle lock switch, front and
rear locker relays, front and rear locker pumps, and
locker indicator switches. To operate both lockers
three requirements need to be met:
1. ignition in the ON position
2. transfer case range sensor indicating 4 “LOW”
range
3. vehicle speed less than 16km/h (10 mph)
The 16km/h (10 mph) engagement is for engage-
ment only. All axles will remain locked if vehicle
speed does not exceed 72 km/h (45 mph).
The instrument cluster has the control logic that
monitors these requirements. If the requirements
are not met the axle lock switch will be disabled.
The axle lock switch receives the enable signals
from the instrument cluster.Any subsequent down-
4
GENERAL INFORMATION

ward press of the axle lock switch will operate the
front locker relay and front locker pump. The first
downward press on the axle lock switch locks the
rear axle, the second downward press locks the
front axle (rear is still locked), the third downward
press unlocks the front axle (rear is still locked), the
fourth downward press locks the front axle (rear
axle is still locked). An upward press on the axle
lock switch at any time will unlock any axle that is
currently locked.
The enabled axle lock switch energizes the locker
relay and voltage is sent to the locker pump to
supply 5 psi of air to the axle allowing the differen-
tial to lock up. The “axle lock” indicator on the
instrument cluster flashes during the transition
state. The instrument cluster is seeking lock feed-
back from the locking indicator switch. With a
successful lock request the “axle lock” indicator will
be illuminated and a chime will sound.
If an axle is engaged the axle lock switch remains
enabled until all axles are unlocked, regardless if
the key is removed from the ignition switch. If the
ignition key is removed and either axle is locked the
instrument cluster “axle lock” indicator to the cor-
responding axle will flash and the chime will sound
three times to alert of battery discharge. Flashing
“axle lock” indicators will continue until axles are
unlocked. Once the axles have been locked it will
remain locked until one of the following happens:
1. an upward press of the axle lock switch for all
locked axles or downward press for front axle
only
2. transfer case is shifted out of 4 “LOW” range
3. vehicle speed exceeds 72 km/h (45 mph)
4. loss of battery power
3.4 USING THE DRBIIIT
Refer to the DRBIIItuser’s guide for instructions
and assistance with reading diagnostic trouble
codes, erasing trouble codes and other DRB func-
tions.
3.5 DRBIIITERROR MESSAGES
Under normal operation, the DRBIIItwill dis-
play one of only two error messages:
– User–Requested WARM Boot or User–Re-
quested COLD Boot
This is a sample of such an error message display:
ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot
Press MORE to switch between this display
and the application screen.
Press F4 when done noting information.
3.5.1 DRBIIITDOES NOT POWER UP
(BLANK SCREEN)
If the LED’s do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage (data link
16-way connector cavity 16). A minimum of 11 volts
is required to adequately power the DRBIIIt. Also,
check for a good ground at the DLC.
If all connections are proper between the
DRBIIItand the vehicle or other devices, and the
vehicle battery is fully charged, and inoperative
DRBIIItmay be the result of faulty cable or vehicle
wiring.
3.5.2 DISPLAY IS NOT VISIBLE
Low temperatures will affect the visibility of the
display. Adjust the contrast to compensate for this
condition.
4.0 DISCLAIMERS, SAFETY
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
5
GENERAL INFORMATION

information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
important to block the wheels on front-wheel drive
vehicles; the parking brake does not hold the drive
wheels.
When servicing a vehicle always wear eye protec-
tion and remove any metal jewelry such as watch-
bands or bracelets that might make an inadvertent
electrical contact.
Additional safety procedures can be found in the
service manual. Following these procedures is very
important to avoid injury.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If is does not, false diagnostic
trouble codes or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the antilock brake system
are intended to be serviced in assembly only. At-
tempting to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLY FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND THE SPECIFICATION LIMITS.
•Follow the vehicle manufacturer’s service speci-
fications at all times.
•Do not use the DRBIIItif it has been damaged.
•Do not use the test leads if the insulation is
damaged or if metal is exposed.
•To avoid electrical shock, do not touch the test
leads, tips or the circuit being tested.
•Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
•Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 - 1.12 megohms
Frequency Measured
Frequency Generated 0-10kHz
Temperature -50 - 600°C
-58 - 1100°F
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
•Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
•Use caution when measuring voltage above 25v
DC or 25v AC.
•Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
•When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
•When measuring current, connect the meter in
series with the load.
•Disconnect the live test lead before disconnecting
the common test lead.
•When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
4.3 WARNING
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is OFF. Failure to do so could
damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not pierce wire insulation; this
will damage it and eventually cause it to fail be-
cause of corrosion.
6
GENERAL INFORMATION

Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second code could be set, making diagnosis of the
original problem more difficult.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
NOTE: After the repair of pump or speed
signal DTC’s, the vehicle must be driven at 25
km/h (15 mph) to clear the DTC from the CAB.
WARNING: BEFORE ROAD TESTING A
VEHICLE, BE SURE THAT ALL
COMPONENTS ARE REASSEMBLED.
DURING THE TEST DRIVE, DO NOT TRY TO
READ THE DRBIIITSCREEN WHILE IN
MOTION. DO NOT HANG THE DRB FROM
THE REAR VIEW MIRROR OR OPERATE IT
YOURSELF. HAVE AN ASSISTANT
AVAILABLE TO OPERATE THE DRBIIIT.
4.4 DIAGNOSIS
1. Your diagnostic test procedure must begin with a
thorough visual inspection of the ABS for dam-
aged components or disconnected connectors.
The brake lamps must be operational prior to
continuing.
2. Connect the DRBIIItto the data link connector
located under the dash. If the DRBIIItdoes not
power up, check the power and ground supplies
to the connector.
3. Select ‘‘Antilock Brakes’’. Turn the ignition on. If
the DRBIIItdisplays ‘‘No Response’’, perform
the proper test.
4. Read and record all ABS diagnostic trouble
codes. If the ‘‘CAB Power Feed Circuit’’ trouble
code is present, it must be repaired prior to
addressing any other DTC’s. If any additional
codes are present, proceed to the appropriate
test.
5. If there are no diagnostic trouble codes present,
select ‘‘Inputs/Outputs’’ and read the brake
switch input as you press and release the brake
pedal. If the display does not match the state of
the pedal, perform the appropriate test. Read the
‘‘G-Switch’’ status, with the vehicle on a level
surface, both switches should read ‘‘CLOSED’’. If
the status is not correct, perform the appropriate
test. If a problem with the ABS warning indica-
tor exists, refer to the appropriate test.
6. If no other problem are found, it will be neces-
sary to road test the vehicle. THE DRBIIIt
MUST NOT BE CONNECTED TO THE
DATA LINK CONNECTOR WHEN ROAD
TESTING FOR PROPER ANTILOCK OP-
ERATION. THE SYSTEM IS DISABLED
WHILE IN DIAGNOSTIC MODE. Perform
several antilock stops from above 50 Km/h (30
mph) and then repeat steps 2, 3, and 4. If any
diagnostic trouble codes are present, proceed to
the appropriate test.
7. The following conditions should be considered
‘‘NORMAL’’ operation, and no repairs should be
attempted to correct them.
– Brake pedal feedback during an ABS stop
(clicking, vibrating)
– Clicking, groaning or buzzing at 10 Km/h (6
mph) (drive off self test)
– Groaning noise during an ABS stop
– Slight brake pedal drop and pop noise when
ignition is initially turned on
– Brake pedal ratcheting down at the end of an
ABS stop
8. If the complaint is “ABS cycling” at the end of a
stop at low speeds, it may be caused by a
marginal wheel speed sensor signal. The sensor
air gap, tone wheel condition, and/or brakes
hanging up are possible causes of this condition.
9. After a road test in which no problems were
found, refer to any Technical Service Bulletins
that may apply.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box)
jumper wires
ohmmeter
voltmeter
test lamp
7
GENERAL INFORMATION

6.0 GLOSSARY OF TERMS
ABS antilock brake system
AC alternating current
BCM Body Control Module
CAB controller antilock brake
CCD Chrysler Collision Detection
DC direct current
DLC data link connector
DRBIIItdiagnostic read-out box
DTC diagnostic trouble code
HCU hydraulic control unit
HZ Hertz
JBLK junction block
JTEC Jeep and Truck Engine Controller
LF left front
LR left rear
PCM Powertrain Control Module
PDC power distribution center
P/M pump motor
RF right front
RR right rear
SCI Serial Communication Interface
SOL Solenoid
WSS wheel speed sensor
8
GENERAL INFORMATION

7.0
DIAGNOSTIC INFORMATION AND
PROCEDURES
9

Symptom:
CAB POWER FEED CIRCUIT
When Monitored and Set Condition:
CAB POWER FEED CIRCUIT
When Monitored: Ignition on. The CAB monitors the Fused B(+) circuit at all times for
proper system voltage.
Set Condition: If the Fused B(+) voltage is missing when the CAB detects that an internal
main driver is not 9on9, the Diagnostic Trouble Code (DTC) is set.
POSSIBLE CAUSES
INTERMITTENT DTC
B(+) CIRCUIT SHORTED TO GROUND
BLOWN FUSE - FUSED B(+) CIRCUIT
CAB - FUSED B(+) CIRCUIT SHORTED TO GROUND
FUSED B(+) CIRCUIT OPEN
NO B+ SUPPLY TO FUSE
CAB - FUSED B(+) CIRCUIT OPEN
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, erase DTC’s.
Turn the ignition off.
Turn the ignition on.
Drive the vehicle above 25 km/h (15 mph) for at least 10 seconds.
Stop the vehicle.
With the DRBIIIt, read DTC’s.
Does the DRBIIItdisplay CAB Power Feed Circuit DTC present right now?
All
Yes →Go To 2
No →Go To 9
2 Turn the ignition off.
Remove and Inspect Fuse 12 in the PDC.
Is the Fuse blown?
All
Yes →Go To 3
No →Go To 6
10
BRAKES (CAB)

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Remove Fuse 12 from the PDC.
Disconnect the CAB harness connector.
Note: Check connector - Clean/repair as necessary.
Using a test light connected to 12 volts, probe the Fused B(+) Circuit.
Does the test light illuminate brightly?
All
Yes →Repair the Fused B(+) Circuit Shorted to Ground.
Perform ABS VERIFICATION TEST - VER 1.
No →Go To 4
4 Turn the ignition off.
Remove Fuse 12 from the PDC.
The CAB must be connected for the results of this test to be valid.
Using a test light connected to 12 volts, probe the Fused B+ circuit at the PDC fuse
terminal.
Does the test light illuminate brightly?
All
Yes →Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No →Go To 5
5 Turn the ignition off.
If there are no potential causes remaining, view repair. All
ContinueReplace the Fuse.
Perform ABS VERIFICATION TEST - VER 1.
6 Turn the ignition off.
Remove Fuse 12 from the PDC.
Disconnect the CAB harness connector.
Note: Check connector - Clean/repair as necessary.
Measure the resistance of the Fused B+ circuit between the PDC fuse terminal and
the CAB connector.
Is the resistance below 5 ohms?
All
Yes →Go To 7
No →Repair the Fused B+ circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
7 Remove Fuse 12 from the PDC.
Turn the ignition on.
Measure the voltage of the Fused B+ supply to Fuse 12 in the PDC.
Is the voltage above 10 volts?
All
Yes →Go To 8
No →Repair the B+ Supply circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
8 If there are no potential causes remaining, view repair. All
Repair Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
11
BRAKES (CAB)
CAB POWER FEED CIRCUIT — Continued

TEST ACTION APPLICABILITY
9 Turn the ignition off.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wire harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Refer to any Hotline letters or Technical Service Bulletins that may apply.
Were any problems found?
All
Yes →Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No →Test Complete.
12
BRAKES (CAB)
CAB POWER FEED CIRCUIT — Continued

Symptom:
CONTROLLER FAILURE
When Monitored and Set Condition:
CONTROLLER FAILURE
When Monitored: Ignition on. The CAB monitors its internal microprocessors for correct
operation.
Set Condition: If the CAB detects an internal fault, the DTC is set.
POSSIBLE CAUSES
GROUND AND POWER CONNECTIONS
GROUND CIRCUIT HIGH RESISTANCE
GROUND CIRCUIT INTERFERENCE
CAB - INTERNAL FAILURE
TEST ACTION APPLICABILITY
1 Inspect for non-factory wiring that may interfere with CAB power or ground circuits.
Disconnect the CAB harness connector.
Inspect the CAB wiring harness for incorrect routing and damage.
Inspect the CAB harness and component connectors for corrosion and damage.
Were any concerns found?
All
Yes →Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No →Go To 2
2 Turn the ignition off.
Disconnect the CAB harness connector.
Note: Check connector - Clean/repair as necessary.
Measure the resistance of the CAB ground circuits to body ground.
Is the resistance below 1.0 ohm?
All
Yes →Go To 3
No →Repair the Ground circuit high resistance.
Perform ABS VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the CAB harness connector.
Note: Check connector - Clean/repair as necessary.
Turn the ignition on.
Turn on all accessories.
Measure the voltage of the Ground circuit.
Is the voltage below 1.0 volts?
All
Yes →Go To 4
No →Repair as necessary. Unsplice any accessories connected to the
CAB ground circuit. Reroute and shield any high voltage cables
away from the CAB ground circuit.
Perform ABS VERIFICATION TEST - VER 1.
13
BRAKES (CAB)

TEST ACTION APPLICABILITY
4 If there are no possible causes remaining, view repair. All
Repair Replace the CAB.
Perform ABS VERIFICATION TEST - VER 1.
14
BRAKES (CAB)
CONTROLLER FAILURE — Continued

Symptom:
G-SWITCH NOT PROCESSABLE
When Monitored and Set Condition:
G-SWITCH NOT PROCESSABLE
When Monitored: Ignition on. The CAB sends a test signal out to the G-switch and
monitors the sense circuits #1 and #2.
Set Condition: If the sense circuits are open for 2 minutes while driving or an otherwise
improper signal is detected at any time, the Diagnostic Trouble Code (DTC) is set.
POSSIBLE CAUSES
G-SWITCH TEST SIGNAL CIRCUIT OPEN
INTERMITTENT DTC
G-SWITCH TEST SIGNAL OR SENSE CIRCUIT SHORT TO VOLTAGE OR GROUND
G-SWITCH SIGNAL CIRCUIT INTERNAL OPEN
CAB - TEST SIGNAL CIRCUIT OPEN
G-SWITCH #1 SENSE CIRCUIT OPEN
G-SWITCH #1 SENSE SWITCH OPEN
CAB - #1 SENSE CIRCUIT OPEN
G-SWITCH #2 SENSE CIRCUIT OPEN
G-SWITCH #2 SENSE SWITCH OPEN
CAB - #2 SENSE CIRCUIT OPEN
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read the status of the G-Switch internal switches.
What is the status of both of the G-Switches?
All
Both G-Switches are closed.
Go To 2
Both G-Switches are open.
Go To 3
Only the #1 G-Switch is open.
Go To 7
Only the #2 G-Switch is open.
Go To 10
15
BRAKES (CAB)

TEST ACTION APPLICABILITY
2 Turn the ignition off.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wire harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Refer to any Hotline letters or Technical Service Bulletins that may apply.
Were any problems found?
All
Yes →Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No →Test Complete.
3 Turn the ignition off.
Disconnect the CAB connector.
Check connector - Clean/repair as necessary.
Disconnect the G-Switch Sensor Connector.
NOTE: Check connector - Clean/repair as necessary.
Measure the resistance of the G-Switch Test Signal circuit.
Is the resistance below 5 ohms?
All
Yes →Go To 4
No →Repair the G-Switch Test Signal Circuit Open.
Perform ABS VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Disconnect the CAB Connector.
Check connector - Clean/repair as necessary.
Disconnect the G-Switch Sensor Connector.
Check connector - Clean/repair as necessary.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Test Signal and both Sense
circuits.
Using a 12-volt test light connected to 12-volts, check the Test Signal and both Sense
circuits.
CAUTION: The test light should not light at any test point.
Does the test light illuminate at any test point?
All
Yes →Repair the G-Switch Test Signal or Sense circuit for a short to
voltage or ground.
Perform ABS VERIFICATION TEST - VER 1.
No →Go To 5
5 Turn the ignition off.
Disconnect the G-Switch Connector.
Check connector - Clean/repair as necessary.
Remove G-Switch from vehicle.
While holding the G-Switch level, measure the resistance of the G-Switch Test Signal
circuit and the G-Switch #1 Sense circuit in the G-Switch connector.
Is the resistance below 5 ohms?
All
Yes →Go To 6
No →Replace G-Switch.
Perform ABS VERIFICATION TEST - VER 1.
16
BRAKES (CAB)
G-SWITCH NOT PROCESSABLE — Continued