brakes CHRYSLER VOYAGER 2001 Service Manual

Symptom:
*NO RESPONSE FROM ECM (PCI BUS) - DIESEL ONLY
POSSIBLE CAUSES
ECM PCI NO RESPONSE
PCI BUS CIRCUIT OPEN
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: As soon as one or more module communicates with the DRB, answer
the question.
With the DRB, enter Body then Body Computer.
With the DRB, enter Anti-Lock Brakes.
With the DRB, enter Body then Electro/Mechanical Cluster (MIC).
With the DRB, enter Passive Restraints then Airbag.
Were you able to establish communications with any of the modules?All
Ye s®Go To 2
No®Refer to symptom PCI Bus Communication Failure in the Com-
munications category.
Perform ROAD TEST VERIFICATION - VER-2.
2 With the DRB read ECM Diagnostic Trouble Codes. This is to ensure power and
grounds to the ECM are operational.
NOTE: If the DRB will not read ECM DTC's, follow the NO RESPONSE TO
ECM (SCI only) symptom path, if vehicle will start. For NO START Condi-
tions follow the no start symptom in the Starting category.
Turn the ignition off.
Disconnect the ECM harness connectors.
Use Scope input cable CH7058, Cable to Probe adapter CH7062, and the red and
black test probes.
Connect the scope input cable to the channel one connector on the DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIIItselect Pep Module Tools.
Select lab scope.
Select Live Data.
Select 12 volt square wave.
Press F2 for Scope.
Press F2 and use the down arrow to set voltage range to 20 volts. Press F2 again
when complete.
Connect the Black lead to ground. Connect the Red lead to the PCI Bus circuit in the
ECM connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?All
Ye s®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No®Repair the PCI Bus circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
401
COMMUNICATION

Symptom:
*NO RESPONSE FROM PCM (PCI BUS)
POSSIBLE CAUSES
PCM PCI NO RESPONSE
PCI BUS CIRCUIT OPEN
POWERTRAIN CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: As soon as one or more module communicates with the DRB, answer
the question.
With the DRB, enter Body then Body Computer.
With the DRB, enter Anti-Lock Brakes.
With the DRB, enter Body then Electro/Mechanical Cluster (MIC).
With the DRB, enter Passive Restraints then Airbag.
Were you able to establish communications with any of the modules?All
Ye s®Go To 2
No®Refer to symptom PCI Bus Communication Failure in the Com-
munications category.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
2 With the DRB read PCM Diagnostic Trouble Codes. This is to ensure power and
grounds to the PCM are operational.
NOTE: If the DRB will not read PCM DTC's, follow the NO RESPONSE TO
PCM (SCI only) symptom path, if vehicle will start. For NO START Condi-
tions follow symptom NO RESPONSE in Starting category.
Turn the ignition off.
Disconnect the PCM C2 harness connector.
Use Scope input cable CH7058, Cable to Probe adapter CH7062, and the red and
black test probes.
Connect the scope input cable to the channel one connector on the DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIIItselect Pep Module Tools.
Select lab scope.
Select Live Data.
Select 12 volt square wave.
Press F2 for Scope.
Press F2 and use the down arrow to set voltage range to 20 volts. Press F2 again
when complete.
Connect the Black lead to the PCM ground. Connect the Red lead to the PCI Bus
circuit in the PCM connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?All
Ye s®Replace the Powertrain Control Module in accordance with the
Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No®Repair the PCI Bus circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
412
COMMUNICATION

INTELLIGENT POWER MODULE C3 (GAS) - NATURAL/RED 20 WAYCAV CIRCUIT FUNCTION
1 Z115 20BK/OR (EATX)
(3.3L/3.8L)GROUND
1 Z115 18BK/OR (EATX)
(2.4L)GROUND
2 F1 18PK/WT (EATX) FCM OUTPUT (UNLOCK-RUN-START)
3 T751 18YL (EATX) IGNITION SWITCH OUTPUT (START)
4 T2 18DG/WT TRS REVERSE SENSE
5 T16 18YL/OR (EATX) TRANSMISSION CONTROL RELAY OUTPUT
6 T15 18YL/BR (EATX) TRANSMISSION CONTROL RELAY CONTROL
7 C3 18DB/YL A/C COMPRESSOR CLUTCH RELAY OUTPUT
8 K31 18BR FUEL PUMP RELAY CONTROL
9 C13 18LB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
10 A104 18YL/RD (EATX) FUSED B(+)
11 - -
12 - -
13 D25 18WT/VT (EATX) PCI BUS (EATX)
14 T752 18DG/OR ENGINE STARTER MOTOR RELAY CONTROL
15 Z116 18BK/VT GROUND
16 K51 18BR/WT AUTOMATIC SHUTDOWN RELAY CONTROL
17 F202 18PK/GY IGNITION SWITCH OUTPUT (RUN-START)
18 K173 18BR/VT RADIATOR FAN RELAY CONTROL
19 F202 18PK/GY IGNITION SWITCH OUTPUT (RUN-START)
20 A109 18OR/RD FUSED B(+)
INTELLIGENT POWER MODULE C4 - BLUE 10 WAYCAV CIRCUIT FUNCTION
1 Z127 12BK/DG (GAS) GROUND
2 T750 12YL/GY ENGINE STARTER MOTOR RELAY OUTPUT
3 K342 16BR/WT (DIESEL) ECM/PCM RELAY OUTPUT
3 K342 16BR/WT (GAS) AUTOMATIC SHUTDOWN RELAY OUTPUT
4 F500 16DG/PK (EXCEPT
MTX))FUSED IGNITION SWITCH OUTPUT (RUN)
5- -
6 D25 16WT/VT (ANTILOCK
BRAKES)PCI BUS
7 A107 12TN/RD (ANTILOCK
BRAKES)FUSED B(+)
8 A111 12DG/RD (ANTILOCK
BRAKES)FUSED B(+)
9 A701 14BR/RD (GAS) B(+) (HAZARD FEED)
9 A710 14BR/RD (DIESEL) B(+) (HAZARD FEED)
10 - -
INTELLIGENT POWER MODULE C5 - BLACK 4 WAYCAV CIRCUIT FUNCTION
1 A1 4RD B(+)
2- -
3- -
4- -
C
O
N
N
E
C
T
O
R
P
I
N
O
U
T
S
1046
CONNECTOR PINOUTS

TABLE OF CONTENTS
1.0 INTRODUCTION.........................................................1
1.1SYSTEM COVERAGE...............................................1
1.2SIX-STEP TROUBLESHOOTING PROCEDURE..........................1
2.0 IDENTIFICATION OF SYSTEM.............................................1
3.0 SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION......................1
3.1TEVES MARK 20 SYSTEM DESCRIPTION..............................1
3.2TRACTION CONTROL SYSTEM (TCS) DESCRIPTION....................1
3.3SYSTEM COMPONENTS.............................................2
3.3.1ABS AND BRAKE WARNING INDICATORS.......................2
3.3.2CONTROLLER ANTILOCK BRAKE (CAB)........................2
3.3.3HYDRAULIC CONTROL UNIT..................................3
3.3.4SWITCHES/SENSORS........................................3
3.3.5SYSTEM INITIALIZATION.....................................3
3.3.6DIAGNOSTIC MODE.........................................4
3.4DIAGNOSTIC TROUBLE CODES......................................4
3.5DRBIIITERROR MESSAGES AND BLANK SCREEN......................4
3.5.1DRBIIITDOES NOT POWER UP................................4
3.5.2DISPLAY IS NOT VISIBLE.....................................4
4.0 DISCLAIMERS, SAFETY, WARNINGS.......................................5
4.1DISCLAIMERS......................................................5
4.2SAFETY...........................................................5
4.2.1TECHNICIAN SAFETY INFORMATION...........................5
4.2.2VEHICLE PREPARATION FOR TESTING.........................5
4.2.3SERVICING SUB-ASSEMBLIES................................5
4.2.4DRBIIITSAFETY INFORMATION...............................5
4.3WARNINGS........................................................6
4.3.1VEHICLE DAMAGE WARNINGS................................6
4.3.2ROAD TESTING A COMPLAINT VEHICLE........................6
4.4DIAGNOSIS........................................................6
5.0 REQUIRED TOOLS AND EQUIPMENT......................................6
6.0 GLOSSARY OF TERMS...................................................7
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES............................9
BRAKES (CAB)
BUS SYSTEM COMMUNICATION FAILURE.................................10
CAB INTERNAL FAILURE................................................11
CLUSTER LAMP FAILURE................................................12
LEFT FRONT SENSOR CIRCUIT FAILURE..................................14
LEFT REAR SENSOR CIRCUIT FAILURE...................................14
RIGHT FRONT SENSOR CIRCUIT FAILURE.................................14
RIGHT REAR SENSOR CIRCUIT FAILURE..................................14
LEFT FRONT WHEEL SPEED SIGNAL FAILURE.............................17
LEFT REAR WHEEL SPEED SIGNAL FAILURE..............................19
PUMP CIRCUIT FAILURE................................................21
RIGHT FRONT WHEEL SPEED SIGNAL FAILURE............................24
i

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions, and graphics
needed to diagnose Mark 20 Antilock Braking Sys-
tem (ABS) and Mark 20 Antilock Braking System
with Traction Control. The diagnostics in this man-
ual are based on the failure condition or symptom
being present at time of diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the CAB. If the DRBIIItdisplays a ªNo
Responseº 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 * placed before the symptom description indi-
cates a concern with no associated DTC.
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; carry over sys-
tems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE
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 procedure manual covers the an-
tilock braking system (ABS) and traction control
system found on: 2001 Chrysler Town and Country,
Dodge Caravan and Grand Caravan.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the controller antilock brake module
is done in six basic steps:
²verification of complaint
²verification of any related symptoms
²symptom analysis
²problem isolation
²repair of isolated problem
²verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
Vehicles equipped with the Teves Mark 20 an-
tilock brake system can be identified by the pres-
ence of the controller antilock brake module located
beneath the master cylinder.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 TEVES MARK 20 SYSTEM
DESCRIPTION
The controller antilock brake module is used to
monitor wheel speeds and to modulate (control)
hydraulic pressure in each brake channel. The
modulated hydraulic pressure is used to prevent
wheel lock-up during braking.
The Teves Mark 20 system uses a diagonal split
hydraulic brake system.
In the standard brake mode
the master cylinder primary circuit supplies pressure
to the right front and left rear wheel brakes, and the
secondary master cylinder circuit supplies pressure
to the left front and right rear wheel brakes.
3.2 TRACTION CONTROL SYSTEM (TCS)
DESCRIPTION
The main purpose of traction control is to reduce
wheel slip and maintain traction at the driven
wheels when road surfaces are slippery. The trac-
tion control system reduces wheel slip by braking
the wheel that is losing traction. The system is
designed to operate at speeds below 56 km/h (35
mph).
The Controller Antilock Brake (CAB) monitors
wheel speeds. If, during acceleration, the module
detects front (drive) wheel slip and the brakes are
not applied, the CAB will enter traction control
mode. Traction control works in the following order
when drive wheel slip is detected.
1. Close the (normally open) isolation valves.
2. Start pump/motor and supply volume/pressure
to front hydraulic circuits (pump runs continu-
ously during traction control).
3. Open and close build and decay valves to main-
tain minimum wheel slip and maximum trac-
tion.
1
GENERAL INFORMATION

The cycling of the build and decay valves is
similar to the ABS except that they work to control
wheel spin by applying brakes. ABS function is to
control wheel skid by releasing brakes.
Two pressure relief valves allow excess fluid vol-
ume to return to the reservoir when not used by the
build/decay cycles. These are required because the
pump supplies more volume than the traction con-
trol system requires.
If at any time the brake pedal is applied during a
traction control cycle, the brake lamp switch will
trigger the CAB to switch off the traction control.
The traction control system will be enabled at
each ignition cycle. It may be turned off by depress-
ing the Traction Control Switch. The traction con-
trol system function lamp will illuminate ªTRAC
OFFº immediately upon depressing the traction
control switch button. Only the ªTRACº portion of
the ªTRAC OFFº indicator will illuminate during a
traction control event. If the CAB calculates that
the brake temperatures are high, the traction con-
trol system will become inoperative until a time-out
period has elapsed. When in this thermal protection
mode, the traction control ªTRAC OFFº lamp will
illuminate; however, a fault will not be registered.
3.3 SYSTEM COMPONENTS
²controller antilock brake (CAB)
²vacuum booster
²master cylinder
²ABS integrated electronic control module/
hydraulic control unit (HCU), valve block assem-
bly: 8 valve solenoids (4 inlet valves, 4 outlet
valves, 2 accumulators) 1 motor, 2 pump
²ABS integrated electronic control module with
traction control same as above but has 10 valve
solenoids.
²4 wheel speed sensor/tone wheel assemblies
²ABS warning indicator
²fuses and wiring harness
²fluid reservoir
²TRAC/TRAC OFF indicator
3.3.1 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. The ABS warning indicator is controlled by the
CAB. The CAB controls the lamp with a command
over the PCI bus.
The ABS Warning Indicator will remain lit during
every key cycle until a circuit or component fault is
repaired and the CAB no longer detects the fault.After repair of a sensor signal fault or a pump motor
fault, the CAB must sense all four wheels at 25
km/h (15 mph) before it will extinguish the ABS and
TRAC OFF Indicators.
The Instrument Cluster will illuminate the ABS
Warning Indicator if it loses communication with
the CAB.
The red BRAKE warning indicator is also located
in the instrument cluster. It can be activated in
several ways. Application of the parking brake or a
low fluid signal from the fluid level switch located in
the master cylinder reservoir will cause the indica-
tor to come on.
3.3.2 CONTROLLER ANTILOCK BRAKE
(CAB)
The Controller Antilock Brake (CAB) is a
microprocessor-based device that monitors wheel
speeds and controls the antilock functions. The
CAB contains two microprocessors that receive
identical sensor signals and then independently
process the information. The results are then com-
pared to make sure that they agree. Otherwise, the
CAB will turn off the antilock and turn on the ABS
amber warning indicator.
The primary functions of the CAB are to:
²detect wheel locking tendencies
²control fluid pressure modulation to the brakes
during antilock stop
²monitor the system for proper operation
²manage traction control functions
²provide communication to the DRBIIItwhile in
diagnostic mode
²store diagnostic information in non-volatile memory
The CAB continuously monitors the speed of each
wheel. When a wheel locking tendency is detected,
the CAB will command the appropriate valve to
modulate brake fluid pressure in its hydraulic unit.
Brake pedal position is maintained during an an-
tilock stop by being a closed system with the use of
2 accumulators. The CAB continues to control pres-
sure in individual hydraulic circuits until a wheel
locking tendency is no longer present. The CAB
turns on the pump motor during an antilock 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.
The CAB inputs include the following:
²diagnostic communication
²four wheel speed sensors
2
GENERAL INFORMATION

²three power feeds: valves, pump and microproces-
sor
²brake switch
²traction control switch
The CAB outputs include the following:
²ABS warning indicator actuation
²12 volts power to wheel speed sensors
²eight valves
²ten valves with traction control
²diagnostic communication
²PCI bus communication
²traction control lamp illumination
3.3.3 HYDRAULIC CONTROL UNIT
The hydraulic control unit (HCU) contains the
valve block assembly, two accumulators, and pump/
motor assembly. The HCU is attached to the CAB.
Valve Block Assembly:The valve block assem-
bly contains valves with four inlet valves and four
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 wheel. If a wheel detects slip, the
inlet valve is closed to prevent and 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 limits (prop-
er slip ratio), the inlet valve will close to hold the
pressure constant. On vehicles which are equipped
with a traction control system, there are two addi-
tional valves that isolate the master cylinder and
rear wheels. During a traction control event the
brakes are applied to reduce wheel slippage.
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 DC-type motor is
controlled by the CAB. The CAB may turn on the
pump motor when an antilock stop is detected. The
pump continues to run during the antilock stop and
is turned off after the stop is complete. Under some
conditions, the pump motor will run to drain the
accumulators during the next drive off. The CAB
monitors the pump motor operation internally.
Accumulators:The accumulators provide tem-
porary fluid storage during an antilock stop and are
drained by the pump motor.
3.3.4 SWITCHES/SENSORS
Master Cylinder:The master cylinder is a stan-
dard tandem compensating port design for ABS and
non ABS systems. Traction control vehicles use a
dual center port master cylinder. For proper trac-
tion control operation the standard master cylinder
must not be used.
A fluid level switch is located in the master
cylinder fluid reservoir. The switch closes when a
low fluid level is detected. The fluid level switch
turns on the brake warning indicator by grounding
the indicator circuit. This switch does not disable
the ABS system.
Wheel Speed Sensors and Tone Wheels:One
active wheel speed sensor (WSS) is located at each
wheel and sends a small signal to the control
module (CAB). This signal is generated when a
toothed sensor ring (tone wheel) passes by a station-
ary wheel speed sensor. The CAB converts the
signals into digital signals for each wheel.
Because of internal circuitry, correct wheel speed
sensor function cannot be determined by a continu-
ity or resistance check through the sensor.
The front wheel speed 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 though the bearing cover and the
rear tone wheel is an integral part of the rear
bearing hub. The wheel speed sensor air gap is not
adjustable. Refer to the service manual for wheel
speed sensor air gap and resistance specifications.
The four wheel speed sensors are serviced indi-
vidually. The front tone wheels are serviced as an
assembly with the outer constant velocity (C.V.)
joint housing. The rear tone wheels are serviced as
an assembly.
Correct antilock system operation is dependent
on tone wheel speed signals from the wheel speed
sensors. The vehicle's wheels and tires should all be
the same size and type to generate accurate signals.
In addition, the tires should be inflated to the
recommended pressure for optimum system opera-
tion. Variation in wheel and tire size or significant
variations in inflation pressure can produce inaccu-
rate wheel speed signals; however, the system will
continue to function when using the mini-spare.
3.3.5 SYSTEM INITIALIZATION
System initialization starts when the key is
turned to ªrunº. At this point, the CAB performs a
complete self-check of all electrical components in
the antilock systems.
Between 8-17 km/h (5-10 mph), a dynamic test is
performed. This will momentarily cycle the inlet
and outlet valves, check wheel speed sensor cir-
cuitry, and run the pump motor at 25 km/h (15
mph). The CAB will try to test the pump motor. If
3
GENERAL INFORMATION

4.3 WARNINGS
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 probe a wire through the
insulation, this will damage it and eventually cause
it to fail because of corrosion.
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.
WARNING: BEFORE ROAD TESTING A
VEHICLE, BE SURE THAT ALL
COMPONENTS ARE REASSEMBLED.
DURING THE TEST DRIVE, DO NOT TRY TO
READ THE DRB SCREEN WHILE IN MOTION.
DO NOT HANG THE DRBIIITFROM 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 system for
damaged components or disconnected connec-
tors. The brake lamps must be operational, and
if they are not, repair them prior to continuing.
2. Connect the DRBIIItto the data link connector,
which is located under the dash to the left of the
steering column. If the DRBIIItdoes not power
up, check the power and ground supplies to the
connector.
3. Turn the ignition on. Select ªAntilock Brakesº. If
the DRBIIItdisplays ªNo Responseº condition
you must diagnose that first.
4. Read and record all ABS diagnostic trouble
codes. If the ªCAB Power Feed Circuitº diagnos-
tic trouble code is present, it must be repaired
prior to addressing any other DTC's. If any
additional DTC's are present, proceed to theappropriate test by locating the matching test in
the Table of Contents and begin to diagnose the
symptom.
5. If there are no diagnostic trouble codes present,
identify the customer complaint. Select ªInputs/
Outputsº 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 proper test by locating the matching test in
the Table of Contents and begin to diagnose the
symptom. If a problem exists with the yellow
ªABSº warning indicator or the red ªBrakeº
indicator exists, refer to the proper tests by
locating the matching test in the Table of Con-
tents and begin to diagnose the symptom. Read
the traction control switch input as you press
and release the switch. If the display does not
match the state of the indicator perform the
proper test by locating the matching test in the
Table of Contents and begin to diagnose the
symptom.
6. If no other problems are found, it will be neces-
sary to road test the vehicle. Perform several
antilock stops from above 50 Km/h (30 mph) and
then repeat step 4. If any diagnostic trouble
codes are present, proceed to the appropriate test.
7. The following conditions should be considered
ªNORMALº operation, and no repairs should be
attempted to correct them.
± Brake pedal feedback during an ABS stop
(clicking, vibrating).
± Clicking, groaning or buzzing at 25 Km/h (15
mph) or 40 Km/h (24 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 ªcyclingº 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 light
6
GENERAL INFORMATION

Symptom:
BUS SYSTEM COMMUNICATION FAILURE
When Monitored and Set Condition:
BUS SYSTEM COMMUNICATION FAILURE
When Monitored: Ignition ON, every 7 ms.
Set Condition: When the CAB does not receive a message from the instrument cluster for
10 seconds.
POSSIBLE CAUSES
CHECK COMMUNICATION TO MIC
CAB-- INTERNAL FAULT
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, attempt to communicate with the MIC
Was the DRB able to I/D or communicate with the MIC?All
Ye s®Go To 2
No®Refer to the Communication category and perform the symptom
Bus +/- Signals Open from the Controller Anti-Lock Brake.
Perform ABS VERIFICATION TEST - VER 1.
2 With the DRB, erase DTC's.
Turn the ignition on and wait approximately 1 minute.
With the DRB, read DTC's.
Did this DTC reappear?All
Ye s®Replace the Controller Anti-Lock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No®Test Complete.
10
BRAKES (CAB)

Symptom:
CAB INTERNAL FAILURE
When Monitored and Set Condition:
CAB INTERNAL 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
CAB - INTERNAL CONCERN
TEST ACTION APPLICABILITY
1 The only possible cause is a CAB internal concern.
If there are no possible causes remaining, view repair.All
View repair.
Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
11
BRAKES (CAB)