BENDIX EC-15 ANTILOCK CONTROLLER ASSY User manual

1
®
Bendix®EC-15™AntiLock Controller Assembly
SD-13-4785
FIGURE 1 - EC-15™ELECTRONIC CONTROLLER
DIAGNOSTICS
WINDOWDISPLAY
MOUNTING
HOLES (4)
DESCRIPTION
GENERAL
Bendix antilock systems utilizing the EC-15™electronic
controllerassemblyprovidefullvehicle,wheelcontrolbraking
for buses, trucks, and truck tractors. By minimizing the
potentialof “brakelock-up” onall wheelsduring aggressive
braking the vehicle retains a high degree of stability and
steerability,and in most casesvehicle stopping distanceis
reduced.
In order to provide full vehicle, wheel control braking, the
EC-15™controllerassembly isused incombination withthe
followingcomponents:
-Four,individualwheel speedsensors
- Four, air pressure modulator valves
-Antilock condition lamp (dashmounted)
PHYSICAL
TheEC-15™controllerelectronics, thatregulatethe function
ofthe antilocksystem,are containedina diecast aluminum
housing and are environmentally protected. The metal
housing, coupled with the design of the digital electronics,
isintended toprovidea highdegreeofprotectionfrom radio
andelectromagnetic interference.
A diagnostics display window with 9 light emitting diodes
(LEDs) and a magnetically actuated reset switch is
incorporated in the housing for troubleshooting and
diagnosticpurposes.
Two types of electrical connectors are currently used to
connect the EC-15™controller assembly to the antilock
system components; a single, 30 pin, Packard Electric,
150series “Metri-pack”or apairof 14pin, Deutsch,HID 30
seriesconnectors.

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FIGURE 2 - EC-15™/CR-15™ANTILOCK SYSTEM
DASHLAMP
RELAY
RETARDER
CONTROL
M-21™
MODULATOR
(4)
FRONT AXLE
SERVICE
CHAMBER
QUICK
RELEASEVALVE
SERIALLINK
EXCITER (4)
WHEELSPEED
SENSOR
SERVICE
BRAKEVALVE
EC-15™
CONTROLLER
CR-15™
ASSEMBLY
AR-1™ANTILOCK
RELAY
TANDEMAXLE
REARAXLE
SERVICE
ACTUATOR

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FIGURE 3 - EC-15™CONTROLLER AND CONNECTOR STYLES
PACKARD30PIN
CONNECTOR DEUTSCH 14 PIN
CONNECTORS
MOUNTING
TheEC-15™controllerisavailablein twodifferent mounting
styles.Onemodelisdesigned tobemounted onanantilock
relayvalvesuchasthe AR-1™valve(seeServiceDataSheet
SD-13-4795).TheAR-1™valveisa modifiedversion of the
R-12™relayvalve. When theEC-15™controller ismounted
onan antilockrelayvalvetheresulting assemblyreceives a
differentdesignation.ForexamplewhentheEC-15™antilock
controller is mounted on the AR-1™valve the resulting
assembly is known as a CR-15™antilock controller relay.
The other EC-15™controller model is intended for bracket
mounting to a frame member and is not attached to an
antilockrelay valve.
CONTROLLER INPUTS/OUTPUTS
The EC-15™controller receives information from several
components in the antilock system and, based on these
inputs, issues commands or delivers information. Some
portions of the EC-15™controller both receive and deliver
commandsand information.
INPUTS
WheelspeedinformationisprovidedtotheEC-15™controller
via a wiring harness from individual wheel speed sensors
located at or in the vehicle wheels. Working in conjunction
with an exciter or tone ring, wheel speed sensors provide
information to the EC-15™controller in the form of an AC
signalwhichvaries involtageandfrequency asthespeed of
thewheel increasesordecreases. TheEC-15™controlleris
designedto receivewheelspeed information,from various
wheel speed sensor models, at the rate of 100 pulses per
wheel revolution. The EC-15™controller is able to
simultaneously receive, and individually interpret, speed
signalsfrom fourwheel speed sensors.
Vehicle poweris suppliedto theEC-15™controller fromthe
ignitionswitchthroughafuseorcircuitbreaker.Theelectrical
groundfor the EC-15™controlleristhe vehiclechassis.
OUTPUTS
Modulators,liketheBendix®M-21™,are themeansbywhich
theEC-15™antilockcontrollerisabletomodifydriverapplied
air pressure to the service brakes. The modulator is an
electricallycontrolledairvalvethatislocatedneartheservice

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FIGURE 4 - EC-15™CONTROLLER MOUNTED ONANAR-1™VALVE
EC-15™
ELECTRONIC
CONTROLLER
AR-1™ANTILOCK
RELAY VALVE
actuator(s)it controlsand isthe lastairvalvethroughwhich
airpasseson itswaytothe brakeactuator.Awiringharness
connects the modulator to the EC-15™antilock controller.
Solenoid valves contained in the modulator provide the
electricalinterfacebetweentheEC-15™controllerelectronics
and the air brake system. The EC-15™controller is able to
simultaneous and independently control four individual
modulatorassemblies.
A dash light and its electrical relay is connected to, and
controlledby, theEC-15™controller andservesasameans
ofadvising thedriverof thecondition oftheantilock system.
A connection to the engine or transmission retarder is
providedon theEC-15™controller whichallowsthe EC-15™
controllertotemporarily“disable”the retarderduringcertain
modesof operation.While theEC-15™controller iscapable
ofthisfunction,andconnectionsareprovided,itisnotalways
used. Use of the retarder disable function is not essential
buthighlyrecommendedforvehiclesequippedwitharetarder.
ThedatalinkfunctionenablestheEC-15™controllerto“report”
its operating condition to a specialized, external computer
in response to certain commands it receives. The EC-15™
controllerdatalinkconfigurationconformstoS.A.E.standard
J1708and theprotocol, orcodedlanguageused,conforms
toS.A.E. standardJ1587. Therearetwo connectionsto the
EC-15™controllerdevotedtothe datalink.WhiletheEC-15™
controller is capable of this function, and connections are
provided, it is not always used. Use of the data link is not
essentialfor the EC-15™controllerto be functional.
OPERATION
GENERAL
The Bendix®EC-15™antilock controller system provides
individualwheel controlbyusing awheel speedsensor and
modulator at each wheel. By monitoring the rate of
decelerationduringbraking, andsubsequentlyadjustingthe
brake application pressure at each wheel, the EC-15™
controller is able to provide improved braking between the
vehicle tire and the road surface it is on, while maintaining
vehiclestability.
Therearaxle brakesarecontrolled completelyindependent
of each other and therefore brake application pressure at
an individual wheel is adjusted solely on the basis of its
behavior on the road surface on which it is traveling. While
eachsteeringaxle brakeisunder thecontrolof anindividual
modulator,theEC-15™controllerdoesnottreatthesebrakes
totally independent of each other. The EC-15™controller
utilizesamodifiedindividualcontrolphilosophyforthesteering
axlebrakes.Thisisdoneinordertominimize “steeringwheel
pull”in theeventeach wheelis travelingon adifferentroad
surface (e.g.; ice close to the curb and a dry crown).
Essentiallythe EC-15™controllercontrols thebraking force
differences between the two brakes. The wheel on dry
pavementis initiallygiven lessbraking forceandis brought
up to optimum during the stop, while the wheel on ice
attemptstomaintainoptimumbrakingduringtheentire stop.

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FIGURE 5 - WS-20™WHEEL SPEED SENSORS
HUBASSEMBLY
WS-20™SPEED
SENSOR
WS-20™ANGLED
SENSOR
EXCITER RING
(100) TOOTH
WS-20™STRAIGHT
SENSOR
PACKARD
CONNECTOR
DEUTSCH
CONNECTOR
In the case of vehicles equipped with tandem rear axles
(6x2, 6x4), the wheel speed sensors are installed at the
wheelson the axlethat is mostlikely tolosetraction first.A
single modulator controls both curb side brakes on the
tandem,and anothermodulatorcontrols bothbrakeson the
driver’s side of the tandem. With this arrangement of the
speedsensors andmodulators, both brakeson oneside of
thetandem aretreated asonesince theywill mostlikely be
on the same type of road surface. (Refer to figure 2)
NON-ANTILOCK BRAKEAPPLICATION
During normal braking, air pressure from the brake valve
enters the control port of the service relay valve (either an
antilock or standard relay). The service relay delivers air
to, and through, the antilock modulator located near the
brakedwheel,andintothebrakeactuator.Theservicebrakes
are thus applied. If the wheel sensors do not detect an
impending wheel lock up, the EC-15™controller does not
initiate any corrective action and the vehicle comes to a
stop in a normal fashion.
ANTILOCK CONTROLLED BRAKE
APPLICATION SYSTEM FULLY OPERATIONAL
Ifa service brakeapplication ismadeand thewheel speed
sensors detect an impending wheel lockup, the EC-15™
controller will immediately begin modification of the brake
application using the antilock modulator(s) at the affected
wheel(s).
Solenoid valves contained in the modulator are energized
andde-energizedbytheEC-15™controllerinordertomodify
thebrake application. Whena solenoidcoil isenergized its
shuttle moves, and depending upon the function of the
specificsolenoid, iteither opensor closes,thereby causing
the exhaust or reapplication of air pressure to the brake
actuator. The solenoids in each modulator are controlled
independently by the EC-15™controller. By opening and
closingthesolenoid valvesintheappropriate modulator, the
EC-15™controllerisactually simulatingwhatthedriverdoes
whenhe“pumpsthebrakes”.Itmustberememberedhowever
thatunlikethe driver, theEC-15™controllerisableto “pump”
eachbrakeonthe vehicleindependentlyandwithfargreater
speedand accuracy.

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FIGURE 5 - M-21™MODULATOR
SOLENOID
CONNECTOR
EXHAUST
SUPPLY
MOUNTING
HOLES DELIVERY
SUPPLY
ANTILOCK SYSTEM OPERATION -
COMPONENT FAILURE
The Bendix®EC-15™controller handles equipment failure
usingaconservativefail-safephilosophy.Anysingleelectrical
failure of a component devoted to antilock braking, results
in simultaneous illumination of the antilock condition lamp
onthe dash,a disablingof allorpart ofthe antilocksystem,
andreversiontostandardbrakingonwheelsnolongerunder
the control of antilock. When coping with wheel equipment
(modulatororwheelspeedsensor/exciter)failure,theEC-15™
controllerdivides and separatesthe brakesdiagonally.For
example;ifthemodulatorattherightfrontwheelhasabroken
wirelead,theEC-15™controllerdisablestheantilockfunction
forBOTHthe rightfront and leftrear wheels. Theantilock
willcontinuetofunctionontheleftfront andrightrearwheels
and will remain under the control of the EC-15™controller.
(Note:Right andleft,front andrear aredeterminedfromthe
driver’sseat. Leftfront isthereforethe cornerclosest tothe
driver).Dependingupon thetypeoffailure anditspositionof
occurrencethe EC-15™controllereither disablesall,oronly
aportion,oftheantilock system.Apowerorcontrollerfailure,
forinstance, will resultin completedisabling of theantilock
system and reversion to standard braking on all wheels.
Two or more failures, regardless of their position of
occurrence, will also result in the disabling of the entire
system.Withthe failedcomponentapproachdescribed,the
vehicle will retain improved braking stability after a single
failure. It should be remembered that the driver will be
advised of the degraded antilock operation via the dash
lamp and that standard air braking will still be available on
those brakes where the antilock has been disabled by the
EC-15™controller.
ANTILOCK WIRING
The wires that carry information and power into and out of
theEC-15™controller are generallygrouped andterminate
at a connector. The wire groups or wire harnesses along
withtheconnectors aremostoftenspecified andorsupplied
bythevehiclemanufacturer.Twoexamplesoftheconnectors
used on the EC-15™controller are illustrated in figures 7 &
8.The wiring harnessesand connectorsare weather proof
and the wires that enter the connector are sealed to the
connector. The wire gauge used in the wire harnesses is
specific to the task performed.
Whendiagnosing wiringinthe antilocksystemthefollowing
generalrulesapplyandshouldbefollowedwhereapplicable:
1. Itis generallyadvisableto replacea wireharnessrather
than repair individual wires in the harness. If a splice
repair must be made, it is important that the splice be
properly soldered with a rosin flux (not acid based flux)
andmadewaterproof.

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2. Do not pierce wire insulation when testing. Check for
power, ground or continuity by disconnecting the
connector and testing the individual pins or sockets in
theconnector.
3. Always check the vehicle hand book for wire and
connectoridentification.Individual wireidentificationwill
differdepending uponthetype ofconnectors inuse, the
vehiclemanufacturer,and thesystem featuresinuse.
4. Whilethe retarderdisable andseriallinkconnections(3
total)are presentonall EC-15™controllersthey are not
alwaysused.
PREVENTATIVEMAINTENANCE
Every3 months; 25,000miles; or900operating hours,
1. Check all wiring and connectors to ensure they are
secureand freefromvisibledamage.
2. AlthoughtheEC-15™controllerincorporatesaselfcheck
diagnostics, the LED display should be inspected to
ensurethat theyare functional.With thevehicle ignition
on,amagnet(800gauss;capableofpickingup3ounces)
held to the LED reset switch should cause all of the
LED’stoilluminate.Ifone ormoreof theLED’sDO NOT
ILLUMINATEandtheantilockconditionlamponthedash
indicates the system is functioning properly, the
non-illuminated LED(s) should be noted for future
reference. Although the diagnostic capabilities will be
limited,thesystem willcontinueto functionasdesigned.
3. Road test the vehicle by making antilock stop from a
vehicle speed of 20 miles per hour. When an antilock
stop is made, the modulator solenoids pulsate and an
audibleburstof aircanbe heardfromoutside ofthecab.
Thewheelsshouldnotenteraprolonged“lock”condition.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
enginebe in operation,EXTREMECAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Useonly the propertools and observe
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems,makecertain to drain the airpressurefrom
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS™
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommendedprocedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix®replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
REMOVING THE EC-15™CONTROLLER
ASSEMBLY
EC-15™CONTROLLERMOUNTEDONANTILOCKRELAY
VALVE
1. Identifyand remove all airlines connected totheunit.
2. Disconnectthe electricalconnector(s) fromthe EC-15™
controller.
3. Note and mark the mounting position of the controller/
relay valve assembly on the vehicle. Loosen, remove
and save the nuts on the mounting hardware that
attaches the controller relay assembly bracket to the
vehicle.Remove the relayvalve andEC-15™controller
assemblyfrom thevehicle.
4. Remove as much contamination as possible from the
exterior of the assembly making sure to keep the
contaminationaway fromtheopen ports.
5. Note and mark the position of the EC-15™controller
relative to the antilock relay valve. Remove and retain
the four cap screws that secure the EC-15™controller
totheantilockrelayvalve.Carefullyseparate theEC-15™
controller from the antilock relay valve making certain
nottodamage thegasketbetweenthe twocomponents.
Peel the gasket from the EC-15™controller or antilock
relayvalveand retainforreuse.Note:Use anewgasket
if damaged during removal or if a new gasket is
immediatelyavailable.

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FIGURE 7 - WIRING SCHEMATIC FOR EC-15™CONTROLLER WITH DEUTSCH CONNECTORS
DASHLAMP RELAY
RETARDER
CONTROL
SPEEDSENSOR
HOLD
EC-15™
CONTROLLER
CONNECTOR 2
EXHAUST SOURCE
CONNECTOR 1 M-21™
MODULATOR
CONNECTOR 2
REAR
CONNECTOR 1
FRONT
TERMINAL TERMINALCONNECTION
1J POWER
1K DASHLAMP(RELAY) 1P GROUND 1N LEFTFRONTMODULATOREXHAUST 1E LEFTFRONTMODULATORHOLD
1M LEFTFRONTMODULATORSOURCE
1F LEFTFRONT SPEEDSIGNAL
1G LEFTFRONTSPEED SIGNALRETURN
1B RETARDERDISABLE 1C RIGHTFRONTMODULATOREXHAUST 1A RIGHTFRONTMODULATORHOLD 1D RIGHTFRONTMODULATORSOURCE 1H RIGHT FRONTSPEEDSIGNAL
1L RIGHTFRONTSPEEDSIGNAL RETURN
2K LEFTREAR SPEEDSIGNAL
2G LEFTREARSPEED SIGNALRETURN
2A LEFTREARMODULATOREXHAUST 2C LEFTREAR MODULATORHOLD 2D LEFTREAR MODULATORSOURCE
2M RIGHTREARSPEED SIGNAL
2L RIGHTREARSPEED SIGNALRETURN
2E RIGHTREARMODULATOREXHAUST 2N RIGHTREARMODULATORHOLD
2F RIGHTREAR MODULATORSOURCE
2B SERIALA 2H SERIAL B
DEUTSCH CONNECTORSVEHICLE RIGHT FRONT
VEHICLE LEFT REAR
CONNECTORONM-21™
MODULATOR

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FIGURE 9 - WIRING SCHEMATIC FOR EC-15™CONTROLLER WITH PACKARD CONNECTOR
RELAY
RETARDER
CONTROL
SPEEDSENSOR
HOLD
EXHAUST SOURCE
M-21™
MODULATOR
TERMINAL TERMINALCONNECTION
1K & 2K POWER
3F DASHLAMP (RELAY)
1A & 2A GROUND
2F LEFTFRONTMODULATOREXHAUST
2G LEFTFRONTMODULATORHOLD 1G LEFTFRONTMODULATORSOURCE
3J LEFT FRONTSPEEDSIGNAL
3H LEFT FRONTSPEEDSIGNAL RETURN
3G RETARDERDISABLE
1H RIGHTFRONTMODULATOREXHAUST
1J RIGHTFRONTMODULATORHOLD
1F RIGHTFRONTMODULATORSOURCE
2H RIGHT FRONTSPEEDSIGNAL 3K RIGHTFRONTSPEED SIGNALRETURN 3E LEFTREAR SPEEDSIGNAL 2C LEFT REARSPEED SIGNALRETURN 1B LEFTREARMODULATOREXHAUST 1C LEFTREAR MODULATORHOLD 1D LEFTREAR MODULATORSOURCE 3D RIGHT REARSPEEDSIGNAL 3C RIGHT REARSPEEDSIGNAL RETURN 2D RIGHTREARMODULATOREXHAUST 2E RIGHTREARMODULATORHOLD 1E RIGHTREARMODULATORSOURCE 3A SERIALA 3B SERIALB 2B NOTUSED
2J NOT USED
PACKARD CONNECTORVEHICLE RIGHT FRONT
VEHICLE LEFT REAR
CONNECTORONM-21™
MODULATOR
POWER
SERIAL
LINK

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BRACKETMOUNTEDEC-15™CONTROLLER
1. Disconnectthe electricalconnector(s) fromthe EC-15™
controller.
2. Note and mark the mounting position of the EC-15™
controlleron the vehicle.Loosen, removeand savethe
nutsonthemountinghardwarethat attachestheEC-15™
controller bracket to the vehicle. Remove the EC-15™
controllerand bracketfrom thevehicle.
3. Removeand retainthefour capscrews that securethe
EC-15™controllerto the bracket.Separate the EC-15™
controllerfrom the bracket.
INSTALLING THE EC-15™CONTROLLER
ASSEMBLY
EC-15™CONTROLLERMOUNTEDONANTILOCKRELAY
VALVE
1. After noting the relationship of the positioning marks
made prior to disassembly, position the gasket on the
EC-15™controller thensecure the EC-15™controllerto
theantilockrelayvalveusingthefourcapscrews.Torque
the cap screws to 50-80 lbs. in.
2. Mount the assembled EC-15™controller and antilock
relay valve on the vehicle and orient it in the position
markedprior toremoval.
3. Reconnect all air lines to the assembly.
4. Reconnect the electrical connector(s) to the EC-15™
controller.
5. Test the antilock relay valve for operation and leakage
prior to placing the vehicle in service.
6. Perform the “Initial Start-up Procedure” in the
TROUBLESHOOTINGsectiontoassure properantilock
systemoperation.
BRACKETMOUNTEDEC-15™CONTROLLER
1. Secure the EC-15™controller to its bracket using the
fourcap screws.Torquethecapscrewsto50-80lbs. in.
2. After noting the positioning marks, mount the EC-15™
controller on the vehicle using the mounting hardware
retainedduringremoval.
3. Connect the electrical connector(s) to the EC-15™
controller.
4. Perform the “Initial Start-up Procedure” in the
TROUBLESHOOTINGsectiontoassure properantilock
systemoperation.
DIAGNOSINGAND LOCATINGASYSTEM
PROBLEM
GENERAL
The EC-15™controller contains self test and diagnostic
circuitry that continuously checks for proper operation of
theentireantilocksystemincluding wiringcontinuity.Adash
lamp,controlledby theEC-15™controller, advisesthedriver
ofthe conditionof the entireantilock system.The condition
ofspecific antilockcomponentsis providedtothemechanic
byaseriesoflabeled,light emittingdiodes(LED’s)displayed
through a “window” in the EC-15™controller housing. No
special tools or equipment are needed to read or interpret
theEC-15™controllerdiagnosticswindow.Itshouldbenoted
that the EC-15™controller diagnostics display is separate
from the antilock condition lamp on the dash. With this
separation, the driver is aware of any problems that occur
butis not confusedby thediagnostic information.Aspecial
feature of the EC-15™controller is the failure latching and
diagnosticsystem. Intermittentproblems, particularlyin the
wheelspeedsensingareacanbe difficulttodiagnose.When
the controller senses an erroneous condition, whether in
the controller electronics, the modulator or wheel speed
sensingareas,itstorestheconditioninnon-volatilememory,
disablestheantilock function,illuminatesthe dashmounted
antilockconditionlampand theappropriatediagnosticLEDs
onthe EC-15™controller.
The failure condition is truly stored and is not cleared by
lossofpower totheEC-15™controller.TheLEDswillre-light
whenpowerisrestoredandremainilluminateduntilthefailure
is corrected. After the actual problem is corrected,
maintenance personnel can clear or reset the EC-15™
controller diagnostics by passing a small magnet over the
RESETpoint inthe diagnostics window.
DIAGNOSTICLEDs
There are nine LEDs plus a magnetically actuated reset
switchin theEC-15™controller diagnosticwindow.Thefirst
fiveLEDs locate aproblemto a specificarea of thevehicle
while the last four indicate the problem component or its
wiring. The LEDs are software driven and are either ON or
OFF depending upon their monitor function. (Note: Right
andleft,front andreararedetermined fromthedriver’sseat.
Leftfront istherefore the cornerclosest tothe driver.)

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LEDoFRONT RedLED
LED o MID Red LED(SEE NOTEBELOW)
LED o REAR RedLED
LEDoRIGHT Red LED
LED o LEFT Red LED
LED o MOD Red LED
LED o SENS Red LED
LED o ECU Red LED
LED o VOLT Green LED
III RESET NoLED
NOTE: The MID LED shown in the chart above is not used
in the diagnostic process for the EC-15™controller
however it will light when a magnet is placed on the
RESET switch in the diagnostic window.
“FRONT”LED
ThisRedLEDilluminatesand latchesONinordertoindicate
the location of a problem component or its wiring. It will
lightin conjunctionwith eitherthe RIGHTor LEFTLED and
the MOD or SENS LED.
“MID” LED
This Red LED is not used in troubleshooting the EC-15™
controller and should light only when a magnet is held on
the RESET switch.
“REAR”LED
ThisRedLEDilluminatesand latchesONinordertoindicate
thelocation ofa problemcomponentoritswiring. Itwill light
in conjunction with either the RIGHT or LEFT LED and the
MOD or SENS LED.
“RIGHT”LED
ThisRedLEDilluminatesand latchesONinordertoindicate
thelocation ofa problemcomponentoritswiring. Itwill light
inconjunction witheitherthe FRONTorREARLEDand the
MOD or SENS LED.
“LEFT”LED
ThisRedLEDilluminatesand latchesONinordertoindicate
thelocation ofa problemcomponentoritswiring. Itwill light
inconjunction witheitherthe FRONTorREARLEDand the
MOD or SENS LED.
“MOD” LED
This Red LED illuminates and latches ON to indicate a
permanent or intermittent open or short circuit in the
solenoids of one of the four modulators or the wiring
connecting it to the system.
“SENS” LED
This Red LED illuminates and latches ON to indicate
permanentor intermittentfailure.The failuresindicated are;
openorshorted wheelspeedsensor,openorshorted wheel
speed sensor wiring, wheel speed signal not present or
does not conform to design criteria.
“ECU” LED
ThisRedLED,when illuminated,indicatesthatthecontroller
itself has failed. It is latched ON for all EC-15™controller
failures except low voltage. For voltages less than 9VDC,
theLED illuminatesto indicate thecontroller isinoperative,
howeverwhenthevoltageagainexceeds 9VDCtheLEDwill
go OUT by itself.
“VOLT”LED
ThisGreen LEDilluminatesandremainsON duringvehicle
operation to indicate that vehicle power is reaching the
controller. If vehicle power is out of range for proper
operation(below 11vdcor above17 vdc)this LEDwill flash
untilpower is broughtinto range.
“RESET”
Beneath the RESET area of the window display is a
magnetically sensitive switch that is used to reset the
diagnostic system. The device will respond to a magnet
whichhas strengthsufficient tolift athree(3)ounceweight.
Holdinga magnetagainstthe RESETwill causeall LEDsto
light during the time the magnet is against it.
FRONT
MID
REAR
RIGHT
LEFT
MOD
SENS
ECU
VOLT
RESET
EC-15™CONTROLLER
DIAGNOSTIC WINDOW

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TROUBLESHOOTING
GENERAL
While the EC-15™controller diagnostic display locates a
specificproblemarea, itisstillnecessarytoconfirmwhether
the problem resides in the component itself or the wiring.
Basically the troubleshooting procedure that follows is
devoted to narrowing the problem to either the wiring or a
specific antilock component.
TROUBLESHOOTING TIPS
1. All troubleshooting begins by observing the antilock
condition lamp on the dash. Troubleshooting should
beginby firstperforming the“Initial Start-upProcedure”
and following the directions contains in it.
2. The troubleshootingtechnicianshouldrecordall findings
andtheactiontakenduringthetroubleshootingprocess.
3. No voltage or resistance tests are performed into the
EC-15™controller. All voltage and resistance tests are
performed by beginning at the wire harness half of the
connectorandmovingAWAYfromtheEC-15™controller
towardanantilocksystemcomponent(modulator,wheel
speed sensor, etc.)

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TURN VEHICLE IGNITION ON.
OBSERVE DASH ANTILOCK
CONDITIONLAMP.
STARTHERE
DASH LAMP DOES NOT BLINK, IT COMES
ONANDREMAINS ON.
ISDASH LAMPILLUMINATED? GOTO SECTIONI
“DASHLAMPTESTING”
GOTO SECTIONII
“INSPECTIONFOR
ILLUMINATEDLED(S)”
DASH LAMP FLASHES AND COMES ON AND
STAYS ON. INCREASE VEHICLE SPEED TO
ABOVE 10 MPH FOR AT LEAST 30 SECONDS
ANDOBSERVETHE DASHLAMP.
DASHLAMP REMAINSON
NO
GO TO SECTION III “INSPECTION
FORILLUMINATED LED(S)”.
THE SYSTEM IS FUNCTIONING NORMALLY.
MAKE NOTES OF THE PARTS REPLACED OR
REPAIREDANDSTEPSTAKENONTHETROUBLE
SHOOTINGSHEET.
TROUBLESHOOTING
INITIALSTART-UPPROCEDURE
YES
NO
NO
YES
YES

14
DISCONNECT WIRE HARNESS CONNECTOR
FROM EC-15™CONTROLLER (FRONT
CONNECTORONLYINFIGURE7)ANDOBSERVE
THEDASH LAMP.
STARTHERE
WITH IGNITION ON, MEASURE VOLTAGE BETWEEN
LAMPRELAYANDGROUND.VOLTAGESHOULDBESAME
AS BATTERY VOLTAGE (SEE FIGURES 7AND 8)
DASHLAMPILLUMINATED? REPLACETHEEC-15™
CONTROLLER
REPLACEFUSE
AND/ORREPAIROR
REPLACE WIRE
HARNESS
CHECKWIRING HARNESSANDRELAYFOR
SHORTSTOGROUND.RECONNECTAND
CHECK/REPLACETHEFOLLOWING:
1.DASH LIGHTBULB
2. RELAY POWER WIRE
3. RELAY
AFTERREPLACINGEACHCOMPONENTTEST
THEDASH LAMP
ISVOLTAGECORRECT?
NO
REPEATTHE“INITIAL
START-UPPROCEDURE”.
TROUBLESHOOTING
SECTION I - DASH LAMP TESTING
YES
NO
YES

15
TROUBLESHOOTING
SECTION II - INSPECTION FOR ILLUMINATED LEDS
STARTHERE
YES(ON) YES
YES
YES
NO(OFF)
NO
NO
NO
GOTO SECTIONIV
“INSPECTIONFOR
ILLUMINATEDLEDS”.
NOTEANDRECORD
THECONDITIONOF
ALL RED LEDS
ARE ANY RED LEDS
ILLUMINATED? GOTOSECTIONV
“TESTINGFORPOWER
TOTHEEC-15™
CONTROLLER”
AREANY RED
LED’S
ILLUMINATED?
CHECKCLOSELY
ANDNOTEIF GREEN
LEDIS ILLUMINATED
INSPECTEC-15™
CONTROLLERFOR
PRESENCEOF
ILLUMINATEDLEDS
ANDRECORD.
GOTOSECTIONV “TESTING
FORPOWER TOTHE EC-15™
CONTROLLER”.
GOTO SECTIONVIII“TESTING
FORFALSEFAILUREINDICATION
- CAUSED BY DASH LAMP
RELAY”.
REPLACE
THEEC-15™
CONTROLLER
ISGREEN LEDFLASHING?

16
TROUBLESHOOTING
SECTION III - INSPECTION FOR ILLUMINATED LED’S
STARTHERE
YES
YES
NO
NO
NO
GOTOSECTION
V“TESTINGFOR
POWERTOTHE
EC-15™
CONTROLLER”.
NOTEANDRECORD
THECONDITIONOF
ALL RED LEDS
ARE ANY RED LEDS
ILLUMINATED?
AREANY RED
LED’S
ILLUMINATED?
ISGREEN, VOLT,LED
ILLUMINATED?
INSPECTTHEEC-15™CONTROLLER
FORPRESENCEOFILLUMINATEDLEDS
ANDRECORD.
GOTOSECTION
V“TESTINGFOR
POWERTOTHE
EC-15™
CONTROLLER”.
GOTOSECTION IX“TESTINGFOR
FALSE FAILUREINDICATION- CAUSED
BYWHEEL SPEEDCOMPONENTS”.
REPLACETHE EC-15™
CONTROLLER
ISGREEN LEDFLASHING?
NO
YES
YES
GOTO SECTIONIV“INSPECTION
FORILLUMINATEDLEDS”.

17
GOTOSECTIONV “TESTING
FORPOWER TOTHE EC-15™
CONTROLLER”.
USINGTHETWOPOSITIONING LEDS
(RIGHT/LEFTFRONT/REAR)GOTO
SECTIONVIIA“TESTINGTHEWHEEL
SPEEDSENSOR”ANDTESTTHE
APPROPRIATESPEED SENSOR.
THE“SENS” LED ISILLUMINATED
USINGTHETWO POSITIONINGLED’S
(RIGHT/LEFTFRONT/REAR)GOTO
SECTIONVIA“TESTING THE
MODULATOR”ANDTESTTHE
APPROPRIATEMODULATOR.
REPLACETHEEC-15™CONTROLLER
ANDREPEATTHE“INITIALSTART-UP
PROCEDURE”.
DOTHEABOVE CONDITIONS
EXIST?
YES
THEREMUSTBEAMINIMUMOFTHREERED
LEDS ILLUMINATED AND OF THE THREE
THEREMUSTBEA“RIGHT”OR“LEFT”,PLUS
A “FRONT” OR “REAR”, PLUS A “MOD” OR
“SENS”.
ISTHIS LEDILLUMINATED?
NOTERED“ECU”LEDIN
EC-15™CONTROLLER
DIAGNOSTICSWINDOW.
NO
YES
NO
NOTETHETHREE
ILLUMINATEDLEDS.
IS“MOD”LEDILLUMINATED
TROUBLESHOOTING
SECTION IV - INSPECTION FOR ILLUMINATED LEDS.
STARTHERE
YES
NO

18
TURNIGNITIONOFF,REFERTOFIGURES7
AND8,DISCONNECTWIREHARNESS
CONNECTORFROMEC-15™CONTROLLER
(FRONTCONNECTORONLYINFIGURE7)
RECONNECTCONNECTORTOEC-15™
CONTROLLER.CHECKTHEVEHICLE
WIRINGFORCONTINUITY.REFERTO
THEVEHICLE SERVICEMANUALAND
CHECKTHEBATTERYVOLTAGE.
REPAIR OR REPLACEAS NECESSARY
ANDREPEATTHE“INITIALSTART-UP
PROCEDURE”
VOLTAGESAMEAS BATTERY
VOLTAGE,MUSTBEBETWEEN
11AND17 VOLTS.
TURNIGNITIONONAND,MEASURE
VOLTAGEBETWEEN BATTERYAND
GROUNDPINS ONWIREHARNESS
CONNECTOR(SEEFIGURES 7AND8).
TROUBLESHOOTING
SECTION V - TESTING FOR POWER TO THE EC-15™CONTROLLER
STARTHERE
YES
NO
REPEATTHE
“INITIALSTART-UP
PROCEDURE”
REPLACEEC-15™
CONTROLLER

19
ARERESISTANCE
VALUESCORRECT?
REPEAT“INITIALSTART-UP
PROCEDURE”.IF THIS
TESTSTEPHASREPEATED
TWICE - REPLACE THE
EC-15™CONTROLLER.
INSPECTCONNECTORAND
RECONNECTTOEC-15™
CONTROLLER.TURNIGNITIONON
AND PASS MAGNET OVER
RESETONEC-15™CONTROLLER.
NOTEREACTIONOFREDLEDS.
PROBECONNECTORWITHVOLT/OHMMETERANDNOTE
THATPROPERRESISTANCEVALUESAREOBTAINEDFOR
MODULATORBEING TESTED.FIGS. 7AND8. RESISTANCE
VALUESHERE FORBENDIX®M-21™MODULATOR(FIG. 5).
HOLDTOSOURCE: READ 3.5TO 5OHMS
EXHAUSTTOSOURCE: READ3.5TO 5OHMS
EXHAUSTTOHOLD: READ 7TO 10OHMS
SOURCETOBATTERYPOWER: NOCONTINUITY
SOURCETOGROUND: NOCONTINUITY
NOTE:SOURCETOBATTERYTESTNOTREQUIREDFOR
CONNECTOR2,(REAR)DEUTSCH CONNECTORFIGURE7.
TESTREARMODULATORON
OPPOSITESIDE OFVEHICLE GO
TOBEGINNINGTHISSECTION
(VI)AND RETEST
TURNIGNITIONOFF.REFERTO
FIGURES7AND8.DISCONNECT
WIREHARNESSCONNECTOR
FROMEC-15™CONTROLLER.
YES
FRONTORREAR
MODULATOR?
GOTOSECTION VIB AND
CONTINUETESTING
NO
REPLACE EC-15™
CONTROLLER
IFFAILUREPERSISTS,REPLACE
THEEC-15™CONTROLLER.
ARE ANY RED LED’S
ILLUMINATED?
GOTO SECTIONIV
“INSPECTIONFOR
ILLUMINATEDRED
LEDS”ANDRETEST.
TROUBLESHOOTING
SECTION VI A - TESTING THE MODULATOR
SAME RED LED’S
ILLUMINATED?
STARTHERE

20
GOTOMODULATOR,INSPECTWIRINGCONNECTOR.
DISCONNECTCONNECTORANDTESTRESISTANCE
BETWEENPINS ONMODULATOR,RESISTANCEVALUES
FORBENDIX®M-21™MODULATOR(FIGURE5).
HOLDTOSOURCE: READ 3.5 TO 5 OHMS
EXHAUSTTOSOURCE: READ 3.5 TO 5 OHMS
EXHAUSTTOHOLD: READ7 TO 10 OHMS
TESTEACHPINTOVEHICLEGROUNDANDNOTE NO
CONTINUITY.
RECONNECTCONNECTORTOMODULATOR.
TURNIGNITIONONANDPASS MAGNETOVER
RESETONEC-15™CONTROLLER.NOTE
REACTIONOF REDLEDS.
ARE ANY RED LED’S
ILLUMINATED?
RESISTANCEREADINGS
CORRECT?
STARTHEREFROM
SECTIONVIA
REPLACETHEMODULATOR
NO
YES
GOTO SECTIONIV“INSPECTION FOR
ILLUMINATEDLEDS”ANDRETEST.
REPAIRORREPLACE
MODULATORWIREHARNESS.
SAME RED LED’S
ILLUMINATED?
REPEATTHE “INITIAL
START-UPPROCEDURE”
TROUBLESHOOTING
SECTION VI B - TESTING THE MODULATOR
NO
YES
NO
YES