Page 1689 of 4284

(5) Disconnect the right rear parking brake cable
from the connector on the intermediate cable (Fig.
110).
(6) To remove the right parking brake cable hous-
ing from the body bracket, slide a 14 mm box end
wrench over the end of cable retainer to compress the
retaining fingers (Fig. 111). The alternate method
using an aircraft type hose clamp will not work on
the right side of the vehicle.(7) Remove the brake shoes from the brake sup-
port plate. (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/BRAKE PADS/SHOES - REMOVAL).
(8) Disconnect parking brake cable from parking
brake actuator lever.
(9) Remove the parking brake cable housing
retainer from the brake support plate using a 14mm
wrench to compress the retaining fingers (Fig. 112).
Remove the cable.
REMOVAL - PARKING BRAKE CABLE (LEFT
REAR)
(1) Raise vehicle on jackstands or centered on a
hoist. (Refer to LUBRICATION & MAINTENANCE/
HOISTING - STANDARD PROCEDURE).
(2) Remove rear tire and wheel assembly.
(3) Remove rear brake drum from the rear wheel
of the vehicle requiring service to the rear park
brake cable.
(4) Create slack in rear park brake cables by lock-
ing out the automatic adjuster as described here.
Grasp an exposed section of front park brake cable
near the equalizer and pull down on it. Then install
a pair of locking pliers on the cable just rearward of
the second body outrigger bracket (Fig. 113).
(5) Disconnect the left rear parking brake cable
from the parking brake cable equalizer (Fig. 114).
Fig. 110 Right Rear Cable Connection To
Intermediate Cable
1 - RIGHT REAR PARKING BRAKE CABLE
2 - LOCKING NUT
3 - INTERMEDIATE PARKING BRAKE CABLE
Fig. 111 Right Park Brake Cable Removal From
Body Bracket
1 - RIGHT REAR BODY BRACKET
2 - PARK BRAKE CABLE
3 - 14MM WRENCH
4 - LEAF SPRING AND BRACKET
Fig. 112 Removing Park Brake Cable From Brake
Support Plate
1 - PARK BRAKE CABLE RETAINER
2 - PARK BRAKE CABLE
3 - 14MM BOX WRENCH
4 - BRAKE SUPPORT PLATE
RSBRAKES - BASE5-63
CABLES (Continued)
Page 1690 of 4284

(6) To remove parking brake cable housing from
the body bracket, slide a 14 mm box end wrench over
retainer end compressing the three fingers (Fig. 115).
Alternate method is to use an aircraft type hose
clamp.
(7) Remove the brake shoes from the brake sup-
port plate. (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/BRAKE PADS/SHOES - REMOVAL).
(8) Disconnect parking brake cable from parking
brake actuator lever.(9) Remove the parking brake cable housing
retainer from the brake support plate using a 14mm
wrench to compress the retaining fingers (Fig. 116).
Fig. 113 Locked Out Park Brake Automatic Adjuster
1 - PARK BRAKE CABLE
2 - REAR BODY OUTRIGGER BRACKET
3 - LOCKING PLIERS
Fig. 114 Parking Brake Cables At Equalizer
1 - EQUALIZER
2 - LEFT REAR PARKING BRAKE CABLE
3 - LOCKING NUT
4 - INTERMEDIATE PARKING BRAKE CABLE
5 - FRONT PARKING BRAKE CABLE
Fig. 115 Parking Brake Cable Removal From Body
Bracket
1 - LEFT REAR PARK BRAKE CABLE
2 - BODY BRACKET
3 - LEAF SPRING MOUNTING BRACKET
4 - CABLE RETAINER
5 - 14MM BOX WRENCH
Fig. 116 Removing Parking Brake Cable From Brake
Support Plate
1 - PARK BRAKE CABLE RETAINER
2 - PARK BRAKE CABLE
3 - 14MM BOX WRENCH
4 - BRAKE SUPPORT PLATE
5 - 64 BRAKES - BASERS
CABLES (Continued)
Page 1691 of 4284

INSTALLATION - PARKING BRAKE CABLE
(FRONT)
(1) Pass front parking brake cable assembly
through hole in floor pan from the inside of the vehi-
cle.
(2) Pass cable strand button through the hole in
the lever (pedal) assembly bracket.
(3) Install cable retainer onto the park brake cable
and then install cable retainer into pedal assembly
bracket.
(4) Install the end of the park brake cable into the
retainer previously installed into the park brake
pedal bracket.
(5) Install cable strand button into the clevis on
the park brake pedal mechanism.
(6) Install the front park brake cable floor pan seal
into hole in floor pan . Seal is to be installed so the
flange on the seal is flush with the floor pan (Fig.
106). Fold carpeting back down on floor.
(7) Raise vehicle.
(8) Insert brake cable and housing into body out-
rigger bracket making certain that housing retainer
fingers lock the housing firmly into place (Fig. 105).
(9) Manually reset the automatic self-adjusting
mechanism tension of the parking brake lever (pedal)
assembly. (Refer to 5 - BRAKES - STANDARD PRO-
CEDURE).
(10) Assemble the park brake cables onto the park
brake cable equalizer (Fig. 104).
(11) Lower vehicle and apply the park brake pedal
1 time. This will seat the parking brake cables.
INSTALLATION - PARKING BRAKE CABLE
(INTERMEDIATE)
(1) Install the ends of the park brake cables
through the frame rails and into the side brackets.
(2) Install the locking nuts at each end of the cable
and securely tighten (Fig. 107) (Fig. 108).
(3) If the vehicle is a short-wheel-base model, it
will be necessary to reinstall the fuel tank to its nor-
mal mounting position. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL TANK -
INSTALLATION).(4) Install the intermediate parking brake cable on
the cable connector at the right rear parking brake
cable (Fig. 108).
(5) Install the intermediate park brake cable on
the cable equalizer (Fig. 107).
(6) Remove the locking pliers from the front park
brake cable. This will activate the automatic adjuster
and correctly adjust the parking brake cables.
(7) Install and position the foam collar on the
parking brake cable to prevent it from rattling
against the vehicle's floor.
(8) Lower the vehicle and apply the park brake
pedal 1 time, this will seat the park brake cables.
INSTALLATION - PARKING BRAKE CABLE
(RIGHT REAR)
(1) Install the rear parking brake cable in the
brake support plate. Insert cable housing retainer
into brake support plate making certain that cable
housing retainer fingers lock the housing and
retainer firmly into place.
(2) Attach the parking brake cable onto the park-
ing brake actuator lever.
(3) Install the brake shoes on the rear brake sup-
port plate. (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/BRAKE PADS/SHOES -
INSTALLATION).
(4) Insert cable housing retainer into body outrig-
ger bracket making certain that cable housing
retainer fingers lock the housing firmly into place.
(5) Connect the right rear parking brake cable to
the connector on the intermediate parking brake
cable (Fig. 110).
(6) Install the brake drum, then the wheel and tire
assembly.
(7) Remove the locking pliers from the front park
brake cable. This will automatically adjust the park
brake cables.
(8) Lower the vehicle.
(9) Apply and release park brake pedal 1 time.
This will seat the park brake cables.
RSBRAKES - BASE5-65
CABLES (Continued)
Page 1692 of 4284

INSTALLATION - PARKING BRAKE CABLE
(LEFT REAR)
(1) Install the rear parking brake cable in the
brake support plate. Insert cable housing retainer
into brake support plate making certain that cable
housing retainer fingers lock the housing and
retainer firmly into place.
(2) Attach the parking brake cable onto the park
brake actuator lever.
(3) Install the brake shoes on the rear brake sup-
port plate. (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/BRAKE PADS/SHOES -
INSTALLATION).
(4) Insert cable housing retainer into body outrig-
ger bracket making certain that cable housing
retainer fingers lock the housing firmly into place.
(5) Connect rear parking brake cable to the equal-
izer bracket (Fig. 114).
(6) Install brake drum, and wheel and tire assem-
bly.
(7) Remove the locking pliers from the front park
brake cable. This will automatically adjust the park
brake cables.
(8) Apply and release park brake pedal 1 time.
This will seat the park brake cables.
ADJUSTMENT - CABLES
The park brake cables on this vehicle have an
automatic self adjuster built into the park brake
pedal mechanism. When the foot operated park brake
pedal is in its released (upward most) position, a
clock spring automatically adjusts the park brake
cables. The park brake cables are adjusted (ten-
sioned) just enough to remove all the slack from the
cables. The automatic adjuster system will not over
adjust the cables causing rear brake drag.
Due to the automatic adjust feature of the park
brake pedal, adjustment of the parking brake cables
on these vehicles relies on proper drum brake and
park brake shoe adjustment. (Refer to 5 - BRAKES/
HYDRAULIC/MECHANICAL/DRUM - ADJUST-
MENTS) and (Refer to 5 - BRAKES/PARKING
BRAKE/SHOES - ADJUSTMENTS).
When the park brake pedal is applied the self
adjuster is by-passed and the pedal operates nor-
mally to engage the park brakes.
When a service procedure needs to be performed on
the park brake pedal or the park brake cables, the
automatic self adjuster can be manually locked out
by the service technician.
5 - 66 BRAKES - BASERS
CABLES (Continued)
Page 1693 of 4284

BRAKES - ABS
TABLE OF CONTENTS
page page
BRAKES - ABS
DESCRIPTION...........................67
OPERATION.............................67
CAUTION...............................69
STANDARD PROCEDURE..................70
ANTILOCK BRAKE SYSTEM BLEEDING.....70
SPECIFICATIONS........................71
FRONT WHEEL SPEED SENSOR
REMOVAL..............................71
INSTALLATION...........................71
REAR WHEEL SPEED SENSOR - AWD
REMOVAL..............................72
INSTALLATION...........................72
REAR WHEEL SPEED SENSOR - FWD
REMOVAL..............................73INSTALLATION...........................74
TONE WHEEL
INSPECTION............................74
TRACTION CONTROL SWITCH
DIAGNOSIS AND TESTING.................74
TRACTION CONTROL SWITCH............74
ICU (INTEGRATED CONTROL UNIT)
DESCRIPTION...........................75
OPERATION.............................75
REMOVAL..............................76
DISASSEMBLY...........................77
ASSEMBLY.............................77
INSTALLATION...........................77
BRAKES - ABS
DESCRIPTION - ANTILOCK BRAKE SYSTEM
This section covers the physical and operational
descriptions and the on-car service procedures for the
Mark 20e Antilock Brake System and the Mark 20e
Antilock Brake System with traction control.
The purpose of the antilock brake system (ABS) is
to prevent wheel lockup under braking conditions on
virtually any type of road surface. Antilock braking is
desirable because a vehicle that is stopped without
locking the wheels retains directional stability and
some steering capability. This allows the driver to
retain greater control of the vehicle during braking.
DESCRIPTION - ELECTRONIC BRAKE
DISTRIBUTION
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking.
The EBD is used in place of a rear proportioning
valve. The EBD system uses the ABS system to con-
trol the slip of the rear wheels in partial braking
range. The braking force of the rear wheels is con-
trolled electronically by using the inlet and outlet
valves located in the integrated control unit (ICU).
DESCRIPTION - TRACTION CONTROL SYSTEM
Traction control reduces wheel slip and maintains
traction at the driving wheels at speeds below 56
km/h (35 mph) when road surfaces are slippery. The
traction control system reduces wheel slip by braking
the wheel that is losing traction.
HYDRAULIC SHUTTLE VALVES
Two pressure relief hydraulic shuttle valves are
included on vehicles with traction control. These
valves are located inside the HCU and cannot be ser-
viced separately from the HCU.
TRACTION CONTROL LAMP
The traction control function lamp is located in the
transmission range indicator display of the instru-
ment cluster, displaying TRAC, TRAC OFF or nei-
ther depending on system mode.
The TRAC OFF lamp is controlled by a Traction
Control Off switch that is a momentary contact type
switch. The Traction Control Off switch is located on
the steering column upper shroud.
OPERATION - ANTILOCK BRAKE SYSTEM
There are a few performance characteristics of the
Mark 20e Antilock Brake System that may at first
seem abnormal, but in fact are normal. These char-
acteristics are described below.
NORMAL BRAKING
Under normal braking conditions, the ABS func-
tions the same as a standard base brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS BRAKING
ABS operation is available at all vehicle speeds
above 3±5 mph. If a wheel locking tendency is
detected during a brake application, the brake sys-
RSBRAKES - ABS5-67
Page 1694 of 4284

tem enters the ABS mode. During ABS braking,
hydraulic pressure in the four wheel circuits is mod-
ulated to prevent any wheel from locking. Each
wheel circuit is designed with a set of electric sole-
noids to allow modulation, although for vehicle sta-
bility, both rear wheel solenoids receive the same
electrical signal. Wheel lockup may be perceived at
the very end of an ABS stop and is considered nor-
mal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into three 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).
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping, or groaning noises heard by the
driver. This is normal and is 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 is 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 than 3 mph or during
an ABS stop where ABS is no longer required. These
conditions 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 sur-
face activates ABS because of the wheel hop caused
by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, 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±30 percent. This means
that the wheel rolling velocity is 25±30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
black tire marks since the wheel never reaches a
fully locked condition. However, tire marks may 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.
The ABS warning lamp will also be on for up to 5
seconds after the ignition is turned on. When the
vehicle is first driven off, a humming may be heard
or felt by the driver at approximately 20±40 kph
(12±25 mph). All of these conditions are a normal
function of ABS as the system is performing a diag-
nosis check.
PREMATURE ABS CYCLING
Symptoms of premature ABS cycling include: click-
ing sounds from the solenoid valves; pump/motor
running; and pulsations in the brake pedal. Prema-
ture ABS cycling can occur at any braking rate of the
vehicle and on any type of road surface. Neither the
red BRAKE warning lamp, nor the amber ABS warn-
ing lamp, illuminate and no fault codes are stored in
the CAB.
Premature ABS cycling is a condition that needs to
be correctly assessed when diagnosing problems with
the antilock brake system. It may be necessary to use
a DRB scan tool to detect and verify premature ABS
cycling.
Check the following common causes when diagnos-
ing premature ABS cycling: damaged tone wheels;
incorrect tone wheels; damaged steering knuckle
wheel speed sensor mounting bosses; loose wheel
speed sensor mounting bolts; excessive tone wheel
runout; or an excessively large tone wheel-to-wheel
speed sensor air gap. Give special attention to these
components when diagnosing a vehicle exhibiting
premature ABS cycling.
After diagnosing the defective component, repair or
replace it as required. When the component repair or
replacement is completed, test drive the vehicle to
verify that premature ABS cycling has been cor-
rected.
OPERATION - ELECTRONIC BRAKE
DISTRIBUTION
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
the rear brake circuit is pulsed. This allows fluid to
enter the low pressure accumulator (LPA) in the
hydraulic control unit (HCU) resulting in a drop in
fluid pressure to the rear brakes. In order to increase
5 - 68 BRAKES - ABSRS
BRAKES - ABS (Continued)
Page 1695 of 4284

the rear brake pressure, the outlet valve is switched
off and the inlet valve is pulsed. This increases the
pressure to the rear brakes. This back-and-forth pro-
cess will continue until the required slip difference is
obtained. At the end of EBD braking (brakes
released) the fluid in the LPA drains back to the
master cylinder by switching on the outlet valve and
draining through the inlet valve check valve. At the
same time the inlet valve is switched on in case of
another brake application.
The EBD will remain functional during many ABS
fault modes. If both the red BRAKE, and amber ABS
warning indicators are illuminated, the EBD may not
be functioning.
OPERATION - TRACTION CONTROL SYSTEM
The traction control module monitors wheel speed.
During acceleration, if the module detects front
(drive) wheel slip and the brakes are not applied, the
module enters traction control mode. Traction control
operation proceeds in the following order:
(1) Close the normally open isolation valves.
(2) Start the pump/motor and supply volume and
pressure to the front (drive) hydraulic circuit. (The
pump/motor runs continuously during traction con-
trol operation.)
(3) Open and close the build and decay valves to
maintain minimum wheel slip and maximum trac-
tion.
The cycling of the build and decay valves during
traction control is similar to that during antilock
braking, except the valves work to control wheel spin
by applying the brakes, whereas the ABS function is
to control wheel skid by releasing the brakes.
If the brakes are applied at anytime during a trac-
tion control cycle, the brake lamp switch triggers the
controller to switch off traction control.
HYDRAULIC SHUTTLE VALVES
Two pressure relief hydraulic shuttle valves allow
pressure and volume to return to the master cylinder
reservoir when not consumed by the build and decay
valves. These valves are necessary because the
pump/motor supplies more volume than the system
requires.
TRACTION CONTROL LAMP
The traction control system is enabled at each igni-
tion cycle. It may be turned off by depressing the
Traction Control Off switch button when the ignition
is in the ON position. The traction control function
lamp (TRAC OFF) illuminates immediately upon
depressing the button.
The traction control function lamp illuminates dur-
ing a traction control cycle, displaying TRAC.If the CAB calculates that the brake temperatures
are high, the traction control system becomes inoper-
ative until a time-out period has elapsed. During this
ªthermo-protection mode,º the traction control func-
tion lamp illuminates TRAC OFF; note that no trou-
ble code is registered.
CAUTION
The ABS uses an electronic control module, the
CAB. This module is designed to withstand normal
current draws associated with vehicle operation.
Care must be taken to avoid overloading the CAB
circuits.
CAUTION: In testing for open or short circuits, do
not ground or apply voltage to any of the circuits
unless instructed to do so for a diagnostic proce-
dure.
CAUTION: These circuits should only be tested
using a high impedance multi-meter or the DRBIIIT
scan tool as described in this section. Power
should never be removed or applied to any control
module with the ignition in the ON position. Before
removing or connecting battery cables, fuses, or
connectors, always turn the ignition to the OFF
position.
CAUTION: The CAB 24-way connector should never
be connected or disconnected with the ignition
switch in the ON position.
CAUTION: Use only factory wiring harnesses. Do
not cut or splice wiring to the brake circuits. The
addition of aftermarket electrical equipment (car
phone, radar detector, citizen band radio, trailer
lighting, trailer brakes, etc.) on a vehicle equipped
with antilock brakes may affect the function of the
antilock brake system.
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.
CAUTION: An attempt to remove or disconnect cer-
tain system components may result in improper
system operation. Only those components with
approved removal and installation procedures in
this manual should be serviced.
RSBRAKES - ABS5-69
BRAKES - ABS (Continued)
Page 1696 of 4284

CAUTION: If welding work is to be performed on the
vehicle, using an electric arc welder, the CAB con-
nector should be disconnected during the welding
operation.
CAUTION: Many components of the ABS System
are not serviceable and must be replaced as an
assembly. Do not disassemble any component
which is not designed to be serviced.
CAUTION: Only the recommended jacking or hoist-
ing positions for this vehicle are to be used when-
ever it is necessary to lift a vehicle. Failure to raise
a vehicle from the recommended locations could
result in lifting a vehicle by the hydraulic control
unit mounting bracket. Lifting a vehicle by the
hydraulic control unit mounting bracket will result
in damage to the mounting bracket and the hydrau-
lic control unit.
CAUTION: Brake fluid will damage painted surfaces.
If brake fluid is spilled on any painted surface,
wash off with water immediately.
STANDARD PROCEDURE - ANTILOCK BRAKE
SYSTEM BLEEDING
The base brake's hydraulic system must be bled
anytime air enters the hydraulic system. The ABS
though, particularly the ICU (HCU), should only be
bled when the HCU is replaced or removed from the
vehicle. The ABS must always be bled anytime it is
suspected that the HCU has ingested air. Under
most circumstances that require the bleeding of the
brakes hydraulic system, only the base brake
hydraulic system needs to be bled.
It is important to note that excessive air in the
brake system will cause a soft or spongy feeling
brake pedal.
During the brake bleeding procedure, be sure the
brake fluid level remains close to the FULL level in
the master cylinder fluid reservoir. Check the fluid
level periodically during the bleeding procedure and
add DOT 3 brake fluid as required.
The ABS must be bled as two independent braking
systems. The non-ABS portion of the brake systemwith ABS is to be bled the same as any non-ABS sys-
tem.
The ABS portion of the brake system must be bled
separately. Use the following procedure to properly
bleed the brake hydraulic system including the ABS.
BLEEDING
When bleeding the ABS system, the following
bleeding sequence must be followed to insure com-
plete and adequate bleeding.
(1) Make sure all hydraulic fluid lines are installed
and properly torqued.
(2) Connect the DRBIIItscan tool to the diagnos-
tics connector. The diagnostic connector is located
under the lower steering column cover to the left of
the steering column.
(3) Using the DRB, check to make sure the CAB
does not have any fault codes stored. If it does, clear
them using the DRB.
WARNING: WHEN BLEEDING THE BRAKE SYSTEM
WEAR SAFETY GLASSES. A CLEAR BLEED TUBE
MUST BE ATTACHED TO THE BLEEDER SCREWS
AND SUBMERGED IN A CLEAR CONTAINER FILLED
PART WAY WITH CLEAN BRAKE FLUID. DIRECT
THE FLOW OF BRAKE FLUID AWAY FROM YOUR-
SELF AND THE PAINTED SURFACES OF THE VEHI-
CLE. BRAKE FLUID AT HIGH PRESSURE MAY
COME OUT OF THE BLEEDER SCREWS WHEN
OPENED.
(4) Bleed the base brake system using the stan-
dard pressure or manual bleeding procedure. (Refer
to 5 - BRAKES - BASE - STANDARD PROCEDURE)
(5) Using the DRB, select ANTILOCK BRAKES,
followed by MISCELLANEOUS, then BLEED
BRAKES. Follow the instructions displayed. When
the scan tool displays TEST COMPLETED, discon-
nect the scan tool and proceed.
(6) Bleed the base brake system a second time.
Check brake fluid level in the reservoir periodically
to prevent emptying, causing air to enter the hydrau-
lic system.
(7) Fill the master cylinder reservoir to the full
level.
(8) Test drive the vehicle to be sure the brakes are
operating correctly and that the brake pedal does not
feel spongy.
5 - 70 BRAKES - ABSRS
BRAKES - ABS (Continued)