
cally cleared from the CAB memory after the identi-
cal fault has not been seen during the next 255 key
cycles of vehicle operation.
CONTROLLER ANTILOCK BRAKE INPUTS
²Four wheel speed sensors.
²Stop lamp switch.
²Ignition switch.
²System relay voltage.
²Ground.
²Diagnostics Communications (CCD)
CONTROLLER ANTILOCK BRAKE OUTPUTS
²ABS warning lamp actuation.
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
lower left side of the instrument pane. 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. When the ignition key is turned to the
on position, the ABS Warning 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.
The CAB turns on the yellow ABS warning lamp by
grounding the circuit.
HYDRAULIC CIRCUITS AND VALVE OPERATION
Through the following operation descriptions the
function of the various hydraulic control valves in the
ABS will be described. The fluid control valves men-
tioned below, control the flow of pressurized brake
fluid to the wheel brakes during the different modes
of ABS braking.
For explanation purposes, all wheel speed sensors
except the right front are sending the same wheel
speed information. The following diagrams show only
the right front wheel in a antilock braking condition.
NORMAL BRAKING HYDRAULIC CIRCUIT AND
SOLENOID VALVE FUNCTION
This condition is the normal operation of the vehi-
cles base brake hydraulic system. The hydraulic sys-
tem circuit diagram (Fig. 11) shows a situation where
no wheel spin or slip is occurring relative to the
speed of the vehicle. The driver is applying the brake
pedal to build pressure in the brake hydraulic system
to apply the brakes and stop the vehicle.
TEVES MARK 20 ABS CIRCUIT AND
SOLENOID VALVE FUNCTION
This hydraulic circuit diagram (Fig. 12) shows the
vehicle in the ABS braking mode. This hydraulic cir-
cuit (Fig. 12) shows a situation where one wheel is
slipping because the driver is attempting to stop the
vehicle at a faster rate than the surface the vehicle's
tires are on will allow. The normally open and nor-
mally closed valves modulate the brake hydraulic
pressure as required. The pump/motor is switched on
so that the brake fluid from the low pressure accu-
mulators is returned to the master cylinder circuits.
The brake fluid will then be routed to either the mas-
ter cylinder or the wheel brake depending on the
position of the normally open valve.
TEVES MARK 20 SECONDARY ABS CIRCUIT
AND SOLENOID VALVE FUNCTION
This hydraulic circuit diagram (Fig. 13) shows the
vehicle in the ABS braking mode. This hydraulic cir-
cuit (Fig. 13) shows a situation where one wheel is
slipping because the driver is attempting to stop the
vehicle at a faster rate than the surface the vehicle's
tires are on will allow. The normally open and nor-
mally closed valves modulate the brake hydraulic
pressure as required. The pump/motor is switched on
so that the brake fluid from the low pressure accu-
mulators is returned to the master cylinder circuits.
The brake fluid will then be routed to either the mas-
ter cylinder or the wheel brake depending on the
position of the normally open valve. A volume of 1.2
cc's of brake fluid is taken in by the lip seal saver
(Fig. 13) to protect the lip seals on the piston of the
master cylinder.
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
PLBRAKES 5 - 75
DESCRIPTION AND OPERATION (Continued)

DRB DIAGNOSTIC SCAN TOOL USAGE
The diagnostics of the ITT Teves Mark 20 ABS sys-
tem used on this vehicle is performed using the DRB
scan tool. Refer to the diagnostics manual covering
the ITT Teves Mark 20 ABS system for the required
diagnostics ans testing procedures and the DRB oper-
ators manual for its proper operational information.
DRB DIAGNOSTIC CONNECTOR
On this vehicle, the diagnostics connector used for
diagnosing the Teves Mark 20 ABS system is located
under the steering column lower cover, to the left
side of the steering column (Fig. 14). The Teves Mark
20 ABS system uses the CCD connector which is
shared by other vehicle diagnostic systems such as
the powertrain control module and air bag.
ABS SYSTEM SELF DIAGNOSTICS
The ITT Teves Mark 20 ABS system is equipped
with a self diagnostic capability which may be used
to assist in the isolation of ABS faults. The features
of the self diagnostics system are described below.
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, suchas the Controller, solenoid continuity, and the system
relay operation. During this check the Amber ABS
Warning Light is turned on for approximately 5 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.
Fig. 12 ABS Mode Hydraulic Circuit
PLBRAKES 5 - 77
DIAGNOSIS AND TESTING (Continued)

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
these inputs to the CAB should be investigated if a
complaint of intermittent warning system operation
is encountered.
(12) Low system voltage. If Low System Voltage is
detected by the CAB, the CAB will turn on the ABS
Warning Lamp until normal system voltage is
achieved. Once normal voltage is seen at the CAB,
normal operation resumes.(13) High system voltage. If high system voltage is
detected by the CAB, the CAB will turn on the
Amber ABS Warning Lamp until normal system volt-
age is achieved. Once normal voltage is again
detected by the CAB, normal ABS operation resumes.
(14) Additionally, any condition which results in
interruption of electrical current to the CAB or mod-
ulator assembly may cause the ABS Warning Lamp
to turn on intermittently.
(15) The body controller can turn on the (yellow)
ABS warning lamp if CCD communication between
the body controller and the CAB is interupted.
TONEWHEEL INSPECTION
CAUTION: The tone wheels used on this vehicle
equipped with the Teves Mark 20 Antilock Brake
System are different then those used on past mod-
els of this vehicle equipped with antilock brakes.
Reduced braking performance will result if this part
is used on earlier model vehicles and an accident
could result. Do not use on pre-1998 model year
vehicles.
Carefully inspect tonewheel at the suspected faulty
wheel speed sensor for missing, chipped or broken
teeth, this can cause erratic speed sensor signals.
Tonewheels should show no evidence of contact
with the wheel speed sensors. If contact was made,
determine cause and correct before replacing the
wheel speed sensor.
Excessive runout of the tonewheel can cause
erratic wheel speed sensor signals. Refer to Tone-
wheel Runout in the Specification Section in this sec-
tion of the service manual for the tonewheel runout
specification. Replace drive shaft assembly or rear
hub/bearing assembly if tonewheel runout exceeds
the specification.
Inspect tonewheels for looseness on their mounting
surfaces. Tonewheels are pressed onto their mounting
surfaces and should not rotate independently from
the mounting surface.
Check the wheel speed sensor head alignment to
the tone wheel. Also check the gap between the speed
sensor head and the tone wheel to ensure it is at
specification. Refer to Wheel Speed Sensor Clearance
in the Specification Section in this section of the ser-
vice manual.
PROPORTIONING VALVE
CAUTION: Proportioning valves should never be
disassembled.
If premature rear wheel skid occurs on a hard
brake application, it could be an indication that a
PLBRAKES 5 - 79
DIAGNOSIS AND TESTING (Continued)

CAUTION: Certain components of the ABS System
are not intended to be serviced individually.
Attempting to remove or disconnect certain system
components may result in improper system opera-
tion. Only those components with approved
removal and installation procedures in this manual
should be serviced.
CAUTION: Brake fluid will damage painted sur-
faces. If brake fluid is spilled on any painted sur-
faces, wash off with water immediately.
CAUTION: When performing any service procedure
on a vehicle equipped with ABS do not apply a 12
volt power source to the ground circuit of the pump
motor in the HCU. Doing this will damage the pump
motor and will require replacement of the entire
HCU.
The following are general cautions which should be
observed when servicing the ABS system and/or
other vehicle systems. Failure to observe these pre-
cautions may result in ABS System component dam-
age.
If welding work is to be performed on the vehicle,
using an electric arc welder, the CAB connector
should be disconnected during the welding operation.
The CAB 25 way connector connector should never
be connected or disconnected with the ignition switch
in the ON position.
Many components of the ABS System are not ser-
viceable and must be replaced as an assembly. Do not
disassemble any component which is not designed to
be serviced.
ABS HYDRAULIC CONTROL UNIT
REMOVE
(1) Disconnect negative (ground) cable from the
battery and isolate cable.
(2) Remove the power distribution center (PDC)
(Fig. 17) from the battery thermogaurd. PDC is
removed by unlatching the two retaining clips hold-
ing it to the thermogaurd and then pulling it straight
up off of the thermogaurd.
(3) Remove vacuum supply hose from speed control
servo (Fig. 18).
(4) Remove the 2 bolts (Fig. 18) mounting the
bracket for the speed control servo to the body.
(5) Remove the wiring harness connector (Fig. 19)
from the speed control servo. Then remove the rout-
ing clip for the speed control servo wiring harness
from the speed control servo mounting bracket.
(6) Lay the speed control servo, with the speed
control cable attached, on top of the engine.(7) Disconnect wiring harness connector from the
brake fluid level sensor on master cylinder reservoir.
Fig. 17 PDC Attachment To Thermogaurd
Fig. 18 Speed Control Servo Bracket Mounting
Fig. 19 Wiring Harness Connection To Speed
Control Servo
5 - 82 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

(2) Unplug the pump motor wiring harness (Fig.
33) from the CAB.
(3) Remove the 4 bolts (Fig. 34) attaching the CAB
to the HCU.
(4) Remove the CAB from the HCU (Fig. 35).
INSTALL
(1) Install the CAB (Fig. 35) on the HCU.
(2) Install the 4 bolts mounting the CAB (Fig. 34)
to the HCU. Tighten the CAB mounting bolts to a
torque of 2 N´m (17 in. lbs.).
(3) Plug the pump/motor wiring harness into the
CAB (Fig. 33).
(4) Install the ICU. Refer to ABS Integrated Con-
trol Unit in the Removal And Installation Section in
this group of the service manual for the Installation
procedure.
(5) Bleed the base brakes and the ABS brakes
hydraulic system. Refer to the Bleeding ABS System
in this section of the manual for the proper bleeding
procedure.(6) Road test vehicle to ensure proper operation of
the base and ABS brake systems.
FRONT WHEEL SPEED SENSOR
NOTE: Proper installation of the Wheel Speed Sen-
sor Cables is critical to continued system opera-
tion. Be sure that cables are installed, routed and
clipped properly. Failure to install speed sensor
cables as shown in the on car service section of
this manual, may result in contact with moving
parts or over extension of cables, resulting in an
open circuit.
REMOVE
(1) Raise vehicle on jack stands or centered on a
frame contact type hoist. See Hoisting in the Lubri-
cation and Maintenance section of this manual, for
the required lifting procedure to be used for this
vehicle.
(2) Remove the tire and wheel assembly from the
vehicle.
(3) Unplug speed sensor cable connector (Fig. 36)
from vehicle wiring harness. Remove clip (Fig. 36)
attaching speed sensor cable connector to vehicle
body.
(4) Remove wheel speed sensor head to steering
knuckle attaching bolt (Fig. 37).
(5) Carefully, remove sensor head from steering
knuckle. If the sensor has seized, due to corrosion,
DO NOT USE PLIERS ON SENSOR HEAD.Use
a hammer and a punch and tap edge of sensor ear,
rocking the sensor side to side until free.
(6) Remove the speed sensor cable assembly grom-
mets from the retaining bracket (Fig. 38). Remove
speed sensor cable routing clip from the frame of the
vehicle (Fig. 38).
Fig. 33 Pump Motor To CAB Wiring Harness
Fig. 34 CAB Attaching Bolts
Fig. 35 Remove/Install CAB
PLBRAKES 5 - 87
REMOVAL AND INSTALLATION (Continued)

INSTALL
(1) Connect the wheel speed sensor cable connector
to the vehicle wiring harness (Fig. 36).
(2) Install the speed sensor cable assembly grom-
mets into the retaining bracket (Fig. 38). Installspeed sensor cable routing clip onto the frame of the
vehicle (Fig. 38).
(3) Install wheel speed sensor to steering knuckle
attaching screw (Fig. 37). Torque the attaching screw
to 7 N´m (60 in. lbs.)
(4) Install the wheel and tire assembly on vehicle.
(5) Road test vehicle to ensure proper operation of
the base and ABS systems.
REAR WHEEL SPEED SENSOR
NOTE: Proper installation of the Wheel Speed Sen-
sor Cables is critical to continued system opera-
tion. Be sure that cables are installed, routed and
clipped properly. Failure to install speed sensor
cables as shown in the on car service section of
this manual, may result in contact with moving
parts or over extension of cables, resulting in an
open circuit.
REMOVE
(1) Raise vehicle on jack stands or centered on a
frame contact type hoist. See Hoisting in the Lubri-
cation and Maintenance section of this manual, for
the required lifting procedure to be used for this
vehicle.
(2) Remove the tire and wheel from the vehicle.
(3) Unplug speed sensor cable connector from vehi-
cle wiring harness (Fig. 39). Remove clip (Fig. 39)
attaching speed sensor cable connector to vehicle
body.
(4) Remove the speed sensor cable routing bracket
from under rear brake flex hose mounting bracket.
Then remove the speed sensor cable from the routing
clips on the rear brake flex hose and chassis brake
tube.
(5) Remove bolt (Fig. 40) attaching the rear wheel
speed sensor to the disc brake adapter. Then remove
Fig. 36 Speed Sensor Cable To Wiring Harness
Connection
Fig. 37 Front Wheel Speed Sensor Attaching Bolt
Fig. 38 Front Wheel Speed Sensor Cable Routing
Fig. 39 Rear Speed Sensor Connection To Vehicle
Wiring Harness
5 - 88 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

bolt attaching speed sensor cable routing bracket to
rear strut assembly (Fig. 40).
(6) Remove speed sensor head from the disc brake
adapter. If the speed sensor head has seized in the
adapter, DO NOT USE PLIERS ON SENSOR HEAD.
INSTALL
(1) Install wheel speed sensor head into disc brake
adapter (Fig. 40).
(2) Install wheel speed sensor attaching bolt (Fig.
40). Tighten the attaching bolt to a torque of 7 N´m
(60 in. lbs.)
(3) Install the brake flex hose and wheel speed
sensor cable routing bracket on the rear strut
bracket (Fig. 40).
(4) Install wheel speed sensor cable into the rout-
ing clips on the rear brake flex hose and chassis
brake tube.
(5) Plug speed sensor cable connector into vehicle
wiring harness (Fig. 39). Install clip (Fig. 39) attach-
ing speed sensor cable connector to vehicle body.
(6) Install the tire and wheel assembly on vehicle.
(7) Road test vehicle to ensure proper operation of
the base and ABS systems.
SPECIFICATIONS
SPEED SENSOR TONE WHEEL RUNOUT
The total indicator runout allowed for both the
front and rear tone wheel measured using a dial indi-
cator is 0.25 mm (.009 in.).
WHEEL SPEED SENSOR TO TONE WHEEL
CLEARANCE
FRONT WHEEL
Minimum Clearance 0.17 mm (0.007 in.)
Maxamum Clearance 1.80 mm (0.072 in.)
REAR WHEEL
Minimum Clearance 0.37 mm (0.015 in.)
Maxamum Clearance 1.50 mm (0.059 in.)
BRAKE FASTENER TORQUE SPECIFICATIONS
DESCRIPTION TORQUE
BRAKE TUBES:
Tube Nuts To Fittings And
Components Except HCU. . . . 17 N´m (145 in. lbs.)
From Master Cylinder To HCU
At HCU Ports.............21N´m(185 in. lbs.)
BRAKE HOSE:
To Caliper Banjo Bolt..........48N´m(35ft.lbs.)
Intermediate Bracket.........12N´m(105 in. lbs.)
MASTER CYLINDER:
To Vacuum Booster
Mounting Nut............28N´m(250 in. lbs.)
BRAKE BOOSTER:
To Dash Panel Mounting Nuts . .28 N´m (250 in. lbs.)
REAR WHEEL CYLINDER:
To Support Plate
Mounting Bolts............13N´m(115in.lbs.)
Bleeder Screw...............10N´m(80in.lbs.)
BRAKE SUPPORT PLATE:
To Axle Mounting Bolts.........75N´m(55ft.lbs.)
REAR DISC BRAKE ADAPTER:
To Axle Mounting Bolts.........75N´m(55ft.lbs.)
DISC BRAKE CALIPER:
Guide Pin Bolts.............22N´m(192 in. lbs.)
Bleeder Screw..............15N´m(125 in. lbs.)
ABS HYDRAULIC CONTROL UNIT:
To Mounting Bracket Bolts.....28N´m(250 in. lbs.)
Bracket To Frame Rail
Mounting Bolt (Top)........18N´m(160 in. lbs.)
Bracket To Frame Rail
Mounting Bolts (Side)......22N´m(200 in. lbs.)
PARKING BRAKE:
Lever Mounting Nuts.........28N´m(250 in. lbs.)
REAR HUB AND BEARING:
To Knuckle Retaining Nut.....217 N´m (160 ft. lbs.)
WHEEL:
Stud Lug Nut........109±150 N´m (80±110 ft. lbs.)
Fig. 40 Speed Sensor Head Mounting And Cable
Routing
PLBRAKES 5 - 89
REMOVAL AND INSTALLATION (Continued)

DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open engine thermostat?1. Refer to On Board Diagnostic in
Group 25. Replace thermostat if
necessary. If a (DTC) has not been
set, the problem may be with the
temperature gauge.
2. Is the temperature gauge (if
equipped) connected to the
temperature gauge coolant sensor
on the engine?2. Check the connector at the
engine coolant sensor. Refer to
Group 8E. Repair as necessary.
3. Is the temperature gauge (if
equipped) operating OK?3. Check Gauge operation. Refer to
Group 8E. Repair as necessary.
4. Coolant level low during cold
ambient temperature, accompanied
by poor heater performance.4. Check coolant level in the coolant
overflow/reserve tank and the
radiator. Inspect the system for
leaks. Repair as necessary. Refer to
WARNINGS outlined in this section
before removing pressure cap.
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.1. Trailer being towed, a steep hill
being climbed, vehicle being
operated in slow moving traffic, or
engine idling during high ambient
(outside) temperatures with air
conditioning on. High altitudes
Could aggravate these conditions.1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and drive the vehicle
without any of the previous
conditions. Observe the temperature
gauge the gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause of the
overheating and repair. Refer to
POSSIBLE CAUSES in this section.
2. Is temperature gauge (if
equipped) reading correctly?2. Check gauge. Refer to Group 8E.
Repair as necessary.
3. Is temperature warning lamp (if
equipped) illuminating
unnecessarily?3. Check warning lamp operation.
Refer to Group 8E. Repair as
necessary.
4. Coolant low in overflow/reserve
tank and radiator?4. Check for coolant leaks and
repair as necessary. Refer to
checking cooling system for leaks in
this group.
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following step 6.5. Tighten cap.
6. Poor seals at radiator cap. 6. (a) Check condition of cap and
cap seals. Refer to Radiator cap
Inspection. Replace cap if
necessary.
6. (b) Check condition of filler neck.
If neck is bent or damaged, replace
neck.
PLCOOLING 7 - 7