STEERING KNUCKLE
The front suspension knuckle is not a repairable
component of the vehicles front suspensionIT MUST
BE REPLACED.If bent, broken or damaged in any
way, do not attempt to straighten or repair the steer-
ing knuckle.
Service replacement of the front hub/bearing
assembly can be done with the front steering knuckle
remaining on the vehicle.
LOWER CONTROL ARM
If damaged, the lower control arm casting is ser-
viced only as a complete component. Inspect lower
control arm for signs of damage from contact with
the ground or road debris. If lower control arm shows
any sign of damage, inspect lower control arm for
distortion.Do not attempt to repair or straighten
a broken or bent lower control arm.
The serviceable components of the lower control
arm are: the ball joint assembly, ball joint assembly
grease seal and control arm bushings. Inspect both
control arm bushings for severe deterioration, and
replace if required. Inspect ball joint per inspection
procedure in this section of the service manual and
replace if required. Service procedures to replace
these components are detailed in the specific compo-
nent removal and installation sections in this group
of the service manual.
BALL JOINT (LOWER)
With the weight of the vehicle resting on the road
wheels, grasp the grease fitting as shown in (Fig. 5)
and with no mechanical assistance or added force
attempt to rotate the grease fitting.
If the ball joint is worn the grease fitting will
rotate easily. If movement is noted, replacement of
the ball joint is recommended.
STABILIZER BAR
Inspect for broken or distorted sway bar bushings,
bushing retainers, and worn or damaged sway bar to
strut attaching links. If sway bar to front suspension
cradle bushing replacement is required, bushing can
be removed from sway bar by opening slit and peel-
ing bushing off sway bar.
HUB AND BEARING ASSEMBLY
The condition of the front hub and bearing assem-
bly is diagnosed using the inspection and testing pro-
cedure detailed below.
The bearing contained in the Unit III front hub/
bearing assembly will produce noise and vibration
when worn or damaged. The noise will generally
change when the bearings are loaded. A road test of
the vehicle is normally required to determine the
location of a worn or damaged bearing.
Find a smooth level road surface and bring the
vehicle up to a constant speed. When vehicle is at a
constant speed, swerve the vehicle back and forth
from the left and to the right. This will load and
unload the bearings and change the noise level.
Where axle bearing damage is slight, the noise is
usually not noticeable at speeds above 30 m.p.h..
SERVICE PROCEDURES
SUSPENSION CRADLE THREAD REPAIR
PROCEDURE
WARNING: When performing this procedure use
only the thread inserts which are specified in the
Mopar Parts Catalog for this repair procedure.
These thread inserts have been specifically devel-
oped for this application and use of other types of
thread inserts can result in an inferior long term
repair.
The threaded holes in the front suspension cradle,
if damaged, can repaired by installing a Heli-Coilt
thread insert.
The threaded holes that are repairable using the
thread insert, are the lower control arm rear bushing
retainer mounting bolt holes, routing bracket attach-
ing locations for the power steering hoses, and brake
hose attachment holes.
This repair procedure now allows the threaded
holes in the suspension crossmember to be repaired,
eliminating the need to replace the crossmember if
damage occurs to one of the threaded holes.
The thread inserts for this application are specified
by part number in the Mopar Parts Catalog.Do not
use a substitute thread insert.
The specific tools and equipment required to install
the thread insert are listed below. Refer to the
Fig. 5 Checking Ball Joint Wear
2 - 12 SUSPENSIONNS
DIAGNOSIS AND TESTING (Continued)
normal. This may indicate:(1)Abnormal loss of
brake fluid in the master cylinder fluid reservoir
resulting from a leak in the hydraulic system.(2)
Brake shoe linings which have worn to a point
requiring replacement.
As the brake fluid drops below the minimum level,
the brake fluid level sensor closes to ground the
brake warning light circuit. This will turn on the red
brake warning light. At this time, master cylinder
fluid reservoir should be checked and filled to the full
mark with DOT 3 brake fluid.If brake fluid level
has dropped below the add line in the master
cylinder fluid reservoir, the entire brake
hydraulic system should be checked for evi-
dence of a leak.
STOP LAMP SWITCH
The stop lamp switch controls operation of the
vehicles stop lamps. Also, if the vehicle is equippedwith speed control, the stop lamp switch will deacti-
vate speed control when the brake pedal is
depressed.
The stop lamp switch controls operation of the
right and left tail, stop and turn signal lamp and
CHMSL lamp, by supplying battery current to these
lamps.
The stop lamp switch controls the lamp operation
by opening and closing the electrical circuit to the
stop lamps.
HUB/BEARING REAR WHEEL
The rear hub and bearing assembly used on this
vehicle is serviceable only as a complete assembly. No
attempt should be made to disassemble a rear hub
and bearing assembly in an effort to repair it.
The rear hub and bearing assembly is attached to
the rear axle using 4 mounting bolts that are remov-
able from the back of the rear hub/bearing.
DIAGNOSIS AND TESTING
BRAKE SYSTEM BASIC DIAGNOSIS GUIDE
SYMPTOMCHART 1
MISC.
COND.CHART 2
WARNING
LIGHTCHART 3
POWER
BRAKESCHART 4
BRAKE
NOISECHART 5
WHEEL
BRAKES
Brake Warning Light On X NO NO
Excessive Pedal Travel 6 X NO O
Pedal Goes To The Floor 6 X
Stop Light On Without Brakes 3
All Brakes Drag 5
Rear Brakes Drag 2 NO NO
Grabby Brakes O X
Spongy Brake Pedal X NO
Premature Rear Brake Lockup 4 NO NO O
Excessive Pedal Effort 1 O
Rough Engine Idle NO O
Brake Chatter (Rough) NO NO X
Surge During Braking NO NO X
Noise During Braking NO NO X
Rattle Or Clunking Noise NO NO X
Pedal Pulsates During Braking NO NO X
Pull To Right Or Left NO NO X
No: Not A Possible Cause X: Most Likely Cause O: Possible Cause
NSBRAKES 5 - 9
DESCRIPTION AND OPERATION (Continued)
(5) With the aid of a helper, apply pressure to the
brake pedal until a pressure of 6895 kPa (1000 psi) is
obtained on the proportioning valve inlet gauge.
Then based on the type of brake system the vehicle is
equipped with and the pressure specification shown
on the following table, compare the pressure reading
on the outlet gauge to the specification. If outlet
pressure at the proportioning valve is not within
specification when required inlet pressure is
obtained, replace the proportioning valve.
(6) Remove the pressure test fittings and pressure
gauges from the proportioning valve.
(7) Install the chassis brake lines in the correct
ports of the proportioning valve.
(8) Install the pressure test fittings and pressure
gauges in the opposite inlet and outlet port of the
height sensing proportioning valve. Repeat steps 4
and 5 for the other proportioning valve.
(9) Remove the pressure test fittings and pressure
gauges from the proportioning valve.
(10) Install the chassis brake lines in the correct
ports of the proportioning valve.
(11) Install the actuator (Fig. 22) on the height
sensing proportioning valve. Adjust the proportioning
valve actuator. See Height Sensing Proportioning
Valve in the Adjustment Section in this group of the
service manual for the adjustment procedure.
(12) Bleed both rear hydraulic circuits at the rear
brakes.
(13) Road test vehicle.
BRAKE FLUID CONTAMINATION
Indications of fluid contamination are swollen or deteri-
orated rubber parts.
Swollen rubber parts indicate the presence of
petroleum in the brake fluid.To test for contamination, put a small amount of
drained brake fluid in clear glass jar. If fluid sepa-
rates into layers, there is mineral oil or other fluid
contamination of the brake fluid.
If brake fluid is contaminated, drain and thor-
oughly flush system. Replace master cylinder, propor-
tioning valve, caliper seals, wheel cylinder seals,
Antilock Brakes hydraulic unit and all hydraulic
fluid hoses.
RED BRAKE WARNING LAMP TEST
For diagnosis of specific problems with the red
brake warning lamp system, refer to Brake System
Diagnostics Chart 2, located in the Diagnosis And
Testing section in this group of the service manual.
TRACTION CONTROL LAMP TEST
The traction control light is tested by cycling the
traction control switch on and off. The traction con-
trol switch used on this vehicle is a momentary con-
tact type switch. The test procedure for the traction
control light is performed as follows: Press the trac-
tion control switch once and the ªTrac Offº lamp will
illuminate. With the ªTrac Offº lamp illuminated,
press the traction control switch again and the ªTrac
Offº lamp will turn off.
If the traction control lamp does not function as
described in the test above, diagnosis of the traction
control switch, lamp, wiring and other related compo-
nents of the traction control system is required.
STOP LAMP SWITCH TEST PROCEDURE
The required procedure for testing the stop lamp
switch is covered in Group 8H, Vehicle Speed Control
System in this service manual. The electrical circuit
tests for stop lamps is covered in Group 8W Rear-
Lighting in this service manual.
WHEEL
BASEDRIVE
TRAINSALES CODEBRAKE SYS-
TEMSPLIT POINT SLOPEINLET PRES-
SURE PSIOUTLET
PRESSURE
PSI
SWB FWD BRA+BGF149DISC/DRUM
W/O ANTILOCKVAR. .30 1000 PSI 250-350 PSI
SWB FWDBRA+BGF
BRB+BGF
BRV+BGF149,159,159HD
DISC/DRUM
WITH ANTILOCK25 BAR .59 1000 PSI660-780
PSI
LWB FWD BRA+BGF149DISC/DRUM
W/O ANTILOCKVAR. .30 1000 PSI 250-350 PSI
LWB FWDBRA+BGF
BRB+BGF
BRV+BGF149,159,159HD
DISC/DRUM
WITH ANTILOCK25 BAR .59 1000 PSI 660-780 PSI
SWB AWD BRE+BGF159DISC/DISC
WITH ANTILOCK25 BAR .36 1000 PSI 525-640 PSI
LWB AWD BRE+BGF159DISC/DISC
WITH ANTILOCK41 BAR .36 1000 PSI 690-800 PSI
NSBRAKES 5 - 19
DIAGNOSIS AND TESTING (Continued)
(8) Remove tension from front park brake cable.
Tension is removed by releasing the locking pliers
from the front park brake cable.
(9) Remove the 3 bolts mounting the wiring junc-
tion block to the instrument panel.
NOTE: When removing the lower mounting bolt,
push the park brake pedal down 5 clicks to access
the lower mounting bolt.
(10) Remove the lower bolt mounting the park
brake pedal to the body.
(11) Remove the forward bolt mounting the park
brake pedal to the body.
(12) Remove the upper bolt mounting the park
brake pedal to the body.
(13) Disconnect the electrical connector for the
brake light switch (Fig. 138).
(14) Pull downward on front park brake cable
while rotating park brake pedal mechanism out from
behind junction block.
(15) Remove park brake pedal release cable (Fig.
138) from park brake mechanism.
(16) Remove the ground switch for the red brake
warning lamp from the park brake pedal mechanism.
(17) Remove front park brake cable button from
park brake pedal mechanism. Tap end housing of
front park brake cable out of park brake pedal mech-
anism (Fig. 138).
INSTALL
(1) Install the ground switch for the red brake
warning lamp on the park brake pedal mechanism
(2) Install park brake cable end housing (Fig. 138)
into park brake pedal mechanism.
(3) Install cable retainer (Fig. 138) onto the park
brake cable strand and then install retainer into
pedal bracket.(4) Install cable strand button into the clevis on
the park brake pedal mechanism.
(5) Install wiring harness connector on red brake
warning lamp ground switch.
(6) Install the park brake release cable on the
release mechanism of the park brake pedal.
(7) Position the park brake pedal mechanism into
its installed position on the body of the vehicle.
(8) Remove the lock-out pin from the park brake
pedal release mechanism.
(9) Loosely install the top bolt (Fig. 138) mounting
the park brake pedal mechanism to the body.
(10) Loosely install the forward bolt (Fig. 138)
mounting the park brake pedal mechanism to the
body.
(11) Loosely install the lower bolt (Fig. 138)
mounting the park brake pedal mechanism to the
body.
(12) Tighten pedal mechanism attaching bolts to
28 N´m (250 in. lbs.).
(13) Verify that the park brake pedal is in the fully
released (full up) position.
(14) Raise vehicle.
(15) Install the front park brake cable on the park
brake cable equalizer.
(16) Lower vehicle.
(17) Remove the lock-out pin (Fig. 138) from the
automatic cable adjuster on the park brake pedal
mechanism.
(18) Install the electrical junction block on the
instrument panel.
(19) Install the reinforcement on the lower instru-
ment panel.
(20) Install the steering column cover on the lower
instrument panel.
(21) Install the left side kick panel.
(22) Install the sill scuff plate on the lower sill of
the left door.
Fig. 137 Locking Out Automatic AdjusterFig. 138 Park Brake Pedal Mounting
NSBRAKES 5 - 59
REMOVAL AND INSTALLATION (Continued)
ABS BRAKES OPERATION AND VEHICLE
PERFORMANCE
This ABS System represents the current state-of-
the-art in vehicle braking systems and offers the
driver increased safety and control during braking.
This is accomplished by a sophisticated system of
electrical and hydraulic components. As a result,
there are a few performance characteristics that may
at first seem different but should be considered nor-
mal. These characteristics are discussed below.
NORMAL BRAKING SYSTEM FUNCTION
Under normal braking conditions, the ABS System
functions the same as a standard brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS SYSTEM OPERATION
If a wheel locking tendency is detected during a
brake application, the brake system will enter the
ABS mode. During ABS braking, hydraulic pressure
in the four wheel circuits is modulated to prevent
any wheel from locking. Each wheel circuit is
designed with a set of electric solenoids to allow mod-
ulation, although for vehicle stability, both rear
wheel solenoids receive the same electrical signal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into four control channels.
During antilock operation of the vehicle's brake sys-
tem the front wheels are controlled independently
and are on two separate control channels and the
rear wheels of the vehicle are controlled together.
The system can build and release pressure at each
wheel, depending on signals generated by the wheel
speed sensors (WSS) at each wheel and received at
the Controller Antilock Brake (CAB).
ABS operation is available at all vehicle speeds
above 3 to 5 mph. Wheel lockup may be perceived at
the very end of an ABS stop and is considered nor-
mal.
VEHICLE HANDLING PERFORMANCE DURING
ABS BRAKING
It is important to remember that an antilock brake
system does not shorten a vehicle's stopping distance
under all driving conditions, but does provide
improved control of the vehicle while stopping. Vehi-
cle stopping distance is still dependent on vehicle
speed, weight, tires, road surfaces and other factors.
Though ABS provides the driver with some steer-
ing control during hard braking, there are conditions
however, where the system does not provide any ben-
efit. In particular, hydroplaning is still possible when
the tires ride on a film of water. This results in the
vehicles tires leaving the road surface rendering the
vehicle virtually uncontrollable. In addition, extremesteering maneuvers at high speed or high speed cor-
nering beyond the limits of tire adhesion to the road
surface may cause vehicle skidding, independent of
vehicle braking. For this reason, the ABS system is
termed Antilock instead of Anti-Skid.
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping and/or groaning noises heard by the
driver. This is normal due to pressurized fluid being
transferred between the master cylinder and the
brakes. If ABS operation occurs during hard braking,
some pulsation may be felt in the vehicle body due to
fore and aft movement of the suspension as brake
pressures are modulated.
At the end of an ABS stop, ABS will be turned off
when the vehicle is slowed to a speed of 3±4 mph.
There may be a slight brake pedal drop anytime that
the ABS is deactivated, such as at the end of the stop
when the vehicle speed is less then 3 mph or during
an ABS stop where ABS is no longer required. These
conditions will exist when a vehicle is being stopped
on a road surface with patches of ice, loose gravel or
sand on it. Also stopping a vehicle on a bumpy road
surface will activate ABS because of the wheel hop
caused by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lock-up, some wheel slip is desired in order to
achieve optimum braking performance. Wheel slip is
defined as follows, 0 percent slip means the wheel is
rolling freely and 100 percent slip means the wheel is
fully locked. During brake pressure modulation,
wheel slip is allowed to reach up to 25 to30%. This
means that the wheel rolling velocity is 25 to 30%
less than that of a free rolling wheel at a given vehi-
cle speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lock-up.
Complete wheel lock up normally leaves black tire
marks on dry pavement. The ABS System will not
leave dark black tire marks since the wheel never
reaches a fully locked condition. Tire marks may
however be noticeable as light patched marks.
START UP CYCLE
When the ignition is turned on, a popping sound
and a slight brake pedal movement may be noticed.
Additionally, when the vehicle is first driven off a
humming may be heard and/or felt by the driver at
approximately 20 to 40 kph (12 to 25 mph). The ABS
warning lamp will also be on for up to 5 seconds
after the ignition is turned on. All of these conditions
are a normal function of ABS as the system is per-
forming a diagnosis check.
5 - 86 BRAKESNS
DESCRIPTION AND OPERATION (Continued)
The primary functions of the (CAB) are:
(1) Detect wheel locking or wheel slipping tenden-
cies by monitoring the speed of all four wheels of the
vehicle.
(2) Illuminate the TRAC lamp in the message cen-
ter on the instrument panel when a traction control
event is occurring.
(3) Control fluid modulation to the wheel brakes
while the system is in an ABS mode or the traction
control system is activated.
(4) Monitor the system for proper operation.
(5) Provide communication to the DRB Scan Tool
while in diagnostic mode.
(6) Store diagnostic information.
(7)The CAB continuously communicates with
the body controller by sending out a message to
the body controller on the CCD Bus. This mes-
sage is used for illumination of the yellow
antilock warning lamp. This is used if the ABS
controller communication is lost in the hard
wire between the body controller and the yel-
low antilock warning lamp. If the body control-
ler does not receive this message from the CAB,
the body controller will illuminate the antilock
yellow warning lamp.
The CAB continuously monitors the speed of each
wheel through the signals generated by the wheel
speed sensors to determine if any wheel is beginning
to lock. When a wheel locking tendency is detected,
the CAB commands the CAB command coils to actu-
ate. The CAB command coils then open and close the
valves in the HCU which modulate brake fluid pres-
sure in some or all of the hydraulic circuits. The CAB
continues to control pressure in individual hydraulic
circuits until a locking tendency is no longer present.
The ABS system is constantly monitored by the
CAB for proper operation. If the CAB detects a fault,
it will turn on the Amber ABS Warning Lamp anddisable the ABS braking system. The normal base
braking system will remain operational.
The CAB contains a self-diagnostic program which
will turn on the Amber ABS Warning Lamp when a
ABS system fault is detected. Faults are then stored
in a diagnostic program memory. There are multiple
fault messages which may be stored in the CAB and
displayed through the DRB Scan Tool. These fault
messages will remain in the CAB memory even after
the ignition has been turned off. The fault messages
can be read and or cleared from the CAB memory by
a technician using the DRB Scan Tool. The fault
occurrence and the fault code will also be automati-
cally cleared from the CAB memory after the identi-
cal fault has not been seen during the next 3500
miles of vehicle operation. Mileage though of the last
fault occurrence will not be automatically cleared.CONTROLLER ANTILOCK BRAKE INPUTS
²Four wheel speed sensors.
²Stop lamp switch.
²Ignition switch.
²System relay voltage.
²Ground.
²Traction Control Switch (If Equipped).
²Diagnostics Communications (CCD)
CONTROLLER ANTILOCK BRAKE OUTPUTS
²C2D Communication To Body Controller And
Instrument Cluster
²ABS warning lamp actuation.
²Traction Control Light (If Equipped).
²Diagnostic communication. (CCD)
ABS WARNING LAMP (YELLOW)
The ABS system uses a yellow colored ABS Warn-
ing Lamp. The ABS warning lamp is located on the
right side of the message center located at the top of
the instrument panel. The purpose of the warning
lamp is discussed in detail below.
The ABS warning lamp will turn on when the CAB
detects a condition which results in a shutdown of
ABS function or when the body controller does not
receive C2D messages from the CAB. When the igni-
tion key is turned to the on position, the ABS Warn-
ing Lamp is on until the CAB completes its self tests
and turns the lamp off (approximately 4 seconds
after the ignition switch is turned on). Under most
conditions, when the ABS warning lamp is on, only
the ABS function of the brake system is affected. The
standard brake system and the ability to stop the car
will not be affected when only the ABS warning lamp
is on.
The ABS warning lamp is controlled by the CAB
and the body controller through a diode located in
the wiring harness junction block. The junction block
is located under the instrument panel to the left of
Fig. 10 Controller Antilock Brake (CAB)
NSBRAKES 5 - 91
DESCRIPTION AND OPERATION (Continued)
TEVES MARK 20 ABS WITH TRACTION
CONTROL± TRACTION CONTROL HYDRAULIC
CIRCUIT ± SOLENOID AND SHUTTLE VALVE
FUNCTION
This hydraulic circuit diagram (Fig. 16) shows a
vehicle equipped with ABS and traction control in
the traction control mode. The hydraulic circuit (Fig.
16) shows a situation where a driven wheel is spin-
ning and brake pressure is required to reduce its
speed. The normally open ASR valve (Fig. 16) is ener-
gized to isolate the brake fluid being pumped from
the master cylinder and to isolate the driven wheel.
Also, the normally open ASR valve bypasses the
pump output back to the master cylinder at a fixed
pressure setting. The normally open and normally
closed valves (Fig. 16) modulate the brake pressure
as required to the spinning wheel.
DIAGNOSIS AND TESTING
ABS GENERAL DIAGNOSTICS INFORMATION
This section contains the information necessary to
diagnose the ITT Teves Mark 20 ABS Brake System.
Specifically, this section should be used to help diag-
nose conditions which result in any of the following:
(1) ABS Warning Lamp turned on.(2) Brakes Lock-up on hard application
Diagnosis of base brake conditions which are obvi-
ously mechanical in nature should be directed to
Group 5 Brakes in this service manual. This includes
brake noise, brake pulsation, lack of power assist,
parking brake, Red BRAKE Warning Lamp lighting,
or vehicle vibration during normal braking.
Many conditions that generate customer com-
plaints may be normal operating conditions, but are
judged to be a problem due to not being familiar with
the ABS system. These conditions can be recognized
without performing extensive diagnostic work, given
adequate understanding of the operating principles
and performance characteristics of the ABS. See the
ABS System Operation Section in this group of the
service manual to familiarize yourself with the oper-
ating principles of the ABS system.
ABS WIRING DIAGRAM INFORMATION
During the diagnosis of the antilock brake system
it may become necessary to reference the wiring dia-
grams covering the antilock brake system and its
components. For wiring diagrams refer to Antilock
Brakes in Group 8W of this service manual. This
group will provide you with the wiring diagrams and
the circuit description and operation information cov-
ering the antilock brake system.
Fig. 15 ABS With Traction Control ABS Braking Hydraulic Circuit
NSBRAKES 5 - 95
DESCRIPTION AND OPERATION (Continued)
START-UP CYCLE
The self diagnostic ABS start up cycle begins when
the ignition switch is turned to the on position. Elec-
trical checks are completed on ABS components, such
as the Controller, solenoid continuity, and the system
relay operation. During this check the Amber ABS
Warning Light is turned on for approximately 4 sec-
onds and the brake pedal may emit a popping sound
and move slightly when the solenoid valves are
checked.
DRIVE-OFF CYCLE
Further Functional testing is accomplished once
the vehicle is set in motion and reaches a speed of
about 20 kph (12 mph.). This cycle is performed only
once after each ignition on/off cycle.
²The pump/motor is activated briefly to verify
function. When the pump/motor is activated a whirl-
ing or buzzing sound may be heard by the driver,
which is normal when the pump/motor is running.
²The wheel speed sensor output is verified to be
within the correct operating range.
ONGOING TESTS
Other tests are performed on a continuous basis.
These include checks for solenoid continuity, wheel
speed sensor continuity and wheel speed sensor out-
put.
ABS DIAGNOSTIC TROUBLE CODES
Diagnostic trouble codes (DTC) are kept in the con-
troller's memory until either erased by the technician
using the DRB or erased automatically after 3500
miles. DTC's are retained by the controller even if
the ignition is turned off or the battery is discon-
nected. More than one DTC can be stored at a time.
The mileage of the most recent occurrence, number of
occurrences and the DTC that was stored is also dis-
played. Most functions of the CAB and the ABS sys-
tem can be accessed by the technician for testing and
diagnostic purposes by using the DRB.
LATCHING VERSUS NON-LATCHING
DIAGNOSTIC TROUBLE CODES
Some DTC's detected by the CAB are latching; the
DTC is latched and ABS braking is disabled until the
ignition switch is reset. Thus ABS braking is non
operational even if the original DTC has disappeared.
Other DTC's are non-latching; any warning lights
that are turned on, are only turned on as long as the
DTC condition exists. As soon as the condition goes
away, the ABS Warning Light is turned off, although
a DTC will be set in most cases.
INTERMITTENT DIAGNOSTIC TROUBLE CODES
As with virtually any electronic system, intermit-
tent electrical problems in the ABS system may be
difficult to accurately diagnose.
Most intermittent electrical problems are caused
by faulty electrical connections or wiring. When an
intermittent fault is encountered, check suspect cir-
cuits for:
A visual inspection for loose, disconnected, or mis-
routed wires should be done before attempting to
diagnose or service the ITT Teves Mark 20 antilock
brake system. A visual inspection will eliminate
unnecessary testing and diagnostics time. A thorough
visual inspection will include the following compo-
nents and areas of the vehicle.
(1) Inspect fuses in the power distribution center
(PDC) and the wiring junction block. Verify that all
fuses are fully inserted into the PDC and wring junc-
tion block. A label on the underside of the PDC cover
identifies the locations of the ABS fuses in the PDC.
(2) Inspect the 25-way electrical connector at the
CAB for damage, spread or backed-out wiring termi-
nals. Verify that the 25-way connector is fully
inserted in the socket on the CAB. Be sure that wires
are not stretched tight or pulled out of the connector.
(3) Verify that all the wheel speed sensor connec-
tions are secure.
(4) Poor mating of connector halves or terminals
not fully seated in the connector body.
(5) Improperly formed or damaged terminals. All
connector terminals in a suspect circuit should be
carefully reformed to increase contact tension.
(6) Poor terminal to wire connection. This requires
removing the terminal from the connector body to
inspect.
(7) Pin presence in the connector assembly
(8) Proper ground connections. Check all ground
connections for signs of corrosion, tight fasteners, or
other potential defects. Refer to wiring diagram man-
ual for ground locations.
(9) Problems with main power sources of the vehi-
cle. Inspect battery, generator, ignition circuits and
other related relays and fuses.
(10) If a visual check does not find the cause of the
problem, operate the car in an attempt to duplicate
the condition and record the trouble code.
(11) Most failures of the ABS system will disable
ABS function for the entire ignition cycle even if the
fault clears before key-off. There are some failure
conditions, however, which will allow ABS operation
to resume during the ignition cycle in which a failure
occurred if the failure conditions are no longer
present. The following conditions may result in inter-
mittent illumination of the ABS Warning Lamp. All
other failures will cause the lamp to remain on until
the ignition switch is turned off. Circuits involving
NSBRAKES 5 - 97
DIAGNOSIS AND TESTING (Continued)