Page 137 of 1285

not over-hone the bore. Don not increase the diame-
ter of the bore more than 0.0254 mm (0.001 inch)
(Fig. 120). If the bore does not clean up within this
specification, a new caliper housing should be
installed.
NOTE: During the honing procedure, coat the
stones and bore with brake fluid. After honing the
bore, carefully clean the seal and boot grooves with
a stiff non-metallic rotary brush. Use extreme care
in cleaning the caliper after honing. Remove all dirt
and grit by flushing the caliper bore with fresh
clean brake fluid; wipe it dry with a clean, lint free
cloth and then clean it a second time.
(6) Inspect the caliper piston for pitting, scratches,
or any physical damage. Replace the piston if there is
evidence of scratches, pitting or physical damage.
CALIPER SEAL AND PISTON INSTALLATION
NOTE: Never use an old piston seal.
(1) Dip the new piston seal in clean brake fluid
and install it in the groove of the caliper bore. The
seal should be started at one area of the groove and
gently worked around and into the groove (Fig. 121)
using only your clean fingers to seat it.
(2) Coat the new piston boot with clean brake fluid
leaving a generous amount inside the boot.(3) Position the dust boot over the piston after
coating it with brake fluid.
CAUTION: Force applied to the piston to seat it in
the bore must be applied uniformly to avoid cock-
ing and binding of the piston.
Fig. 119 Removing Piston Seal
1 ± PLASTIC TRIM STICK
2 ± CALIPER
3 ± PISTON SEAL GROOVE
4 ± PISTON SEALFig. 120 Honing Brake Caliper Piston Bore
1 ± CALIPER
2 ± CALIPER BORE
3 ± SPECIAL TOOL C-4095
Fig. 121 Installing New Piston Seal
1 ± CALIPER
2 ± PISTON SEAL
3 ± SEAL GROOVE
5 - 58 BRAKESPL
DISASSEMBLY AND ASSEMBLY (Continued)
Page 138 of 1285

(4) Install piston into caliper bore pushing it past
the piston seal until it bottoms in the caliper bore
(Fig. 122).
(5) Position the dust boot into the counterbore of
the caliper assembly piston bore.
(6) Using a hammer and Installer, Special Tool
C-4689, and Handle, Special Tool C-4171, drive the
boot into the counterbore of the caliper (Fig. 123).
(7) Install the brake shoes.
(8) Reinstall the caliper on the vehicle and bleed
the brakes as necessary. Follow the installation pro-
cedure found in DISC BRAKE CALIPER in the
REMOVAL AND INSTALLATION section in this sec-
tion of this service manual group.
CLEANING AND INSPECTION
BRAKE TUBES AND HOSES
Flexible rubber hose is used at both front and rear
brakes. Inspection of brake hoses should be per-
formed whenever the brake system is serviced and
every 7,500 miles or 12 months, whichever comes
first (every engine oil change). Inspect hydraulic
brake hoses for severe surface cracking, scuffing,
worn spots or physical damage. If the fabric casing of
the rubber hose becomes exposed due to cracks or
abrasions in the rubber hose cover, the hose should
be replaced immediately. Eventual deterioration of
the hose can take place with possible burst failure.
Faulty installation can cause twisting, resulting in
wheel, tire, or chassis interference.The steel brake tubing should be inspected period-
ically for evidence of corrosion, physical damage or
contact with moving or hot components of the vehi-
cle.
DISC BRAKES (FRONT)
BRAKE SHOES
Clean the front brake shoes and calipers with a
water-dampened cloth or with a brake cleaner. Do
not use a petroleum based product.
If a visual inspection does not adequately deter-
mine the condition of the lining, a physical check will
be necessary.
Remove the front disc brake shoes. Refer to DISC
BRAKE SHOES in the REMOVAL AND INSTALLA-
TION section in this section of this service manual
group.
The combined brake shoe and lining material
thickness should be measured at the thinnest part of
the assembly.
When a set of brake shoes are worn to a total
thickness of approximately 7.95 mm (5/16 inch) or
less, they should be replaced.
Replace both brake shoe assemblies (inboard and
outboard). It is necessary that both front wheel sets
be replaced whenever brake shoe assemblies on
either side are replaced.
Fig. 122 Installing Piston Into Caliper Bore
1 ± BOOT
2 ± PISTON
3 ± CALIPER
Fig. 123 Installing Dust Boot In Caliper Counterbore
1 ± HAMMER
2 ± SPECIAL TOOL C-4171
3 ± SPECIAL TOOL C-4689
4 ± CALIPER
PLBRAKES 5 - 59
DISASSEMBLY AND ASSEMBLY (Continued)
Page 139 of 1285

If the brake shoe assemblies do not require
replacement, reinstall the assemblies making sure
each brake shoe is returned to the original position.
Refer to DISC BRAKE SHOES in the REMOVAL
AND INSTALLATION section in this section of this
service manual group.
CALIPER INSPECTION
Check for brake fluid leaks in and around the boot
area. Check for any ruptures, brittleness or damage
to the piston dust boot. If the boot is damaged, or a
fluid leak is visible, disassemble the caliper assembly
and install a new seal and boot, and a piston if it is
scored. Refer to DISC BRAKE CALIPER in the DIS-
ASSEMBLY AND ASSEMBLY section in this section
of this service manual group.
Check the guide pin dust boots to determine if they
are in good condition. Replace if they are damaged,
dry, or found to be brittle. Refer to DISC BRAKE
CALIPER in the DISASSEMBLY AND ASSEMBLY
section in this section of this service manual group.
DISC BRAKES (REAR)
BRAKE SHOES
Clean the rear brake shoes and calipers with a
water-dampened cloth or with a brake cleaner. Do
not use a petroleum based product.
If a visual inspection does not adequately deter-
mine the condition of the lining, a physical check will
be necessary.
Remove the rear disc brake shoes. Refer to DISC
BRAKE SHOES in the REMOVAL AND INSTALLA-
TION section in this section of this service manual
group.
The combined brake shoe and lining material
thickness should be measured at the thinnest part of
the assembly.
When a set of brake shoes are worn to a total
thickness of approximately 7.0 mm (9/32 inch) or
less, they should be replaced.
Replace both brake shoe assemblies (inboard and
outboard). It is necessary that both front wheel sets
be replaced whenever brake shoe assemblies on
either side are replaced.
If the brake shoe assemblies do not require
replacement, reinstall the assemblies making sure
each brake shoe is returned to the original position.
Refer to DISC BRAKE SHOES in the REMOVAL
AND INSTALLATION section in this section of this
service manual group.
CALIPER INSPECTION
Check for brake fluid leaks in and around the boot
area. Check for any ruptures, brittleness or damage
to the piston dust boot. If the boot is damaged, or afluid leak is visible, disassemble the caliper assembly
and install a new seal and boot, and a piston if it is
scored. Refer to DISC BRAKE CALIPER in the DIS-
ASSEMBLY AND ASSEMBLY section in this section
of this service manual group.
Check the guide pin dust boots to determine if they
are in good condition. Replace if they are damaged,
dry, or found to be brittle. Refer to DISC BRAKE
CALIPER in the DISASSEMBLY AND ASSEMBLY
section in this section of this service manual group.
DRUM BRAKES (REAR)
BRAKE SHOES
Clean the rear brake shoes and springs with a
water-dampened cloth or with a brake cleaner. Do
not use a petroleum based product.
Rear brake shoe lining should show contact across
the entire width of the lining and also from the heel
to the toe of the lining. Replace the shoes if noted
otherwise.
Brake shoes with lack of contact at the toe or heel
of the brake shoe lining may be improperly ground.
Clean and inspect the brake support plate and
shoe adjuster screw. Apply a thin coat of Mopart
Multi-Purpose Lubricant or equivalent to the threads
of the self-adjuster (Fig. 124). Replace the adjuster
screw if it is corroded.
NOTE: Adjuster screws are different side-to-side.
Left side adjuster screws have left-hand threads
and right side adjuster screws have right-handed
threads.
If the old brake shoe return or hold down springs
have overheated or are damaged, replace them. Over-
heating indications are paint discoloration or dis-
torted end coils.
Fig. 124 Adjuster Screw And Lever (Typical)
1 ± OUTBOARD FORWARD
2 ± SELF ADJUSTER
3 ± OUTBOARD REAR
4 ± SELF ADJUSTER LEVER
5 - 60 BRAKESPL
CLEANING AND INSPECTION (Continued)
Page 140 of 1285

WHEEL CYLINDER
With the brake drums removed, inspect the wheel
cylinder boots for evidence of a brake fluid leak.
Visually check the boots for cuts, tears, or heat
cracks. If any of these conditions exist, the wheel cyl-
inders should be completely cleaned, inspected and
new parts installed.
If a wheel cylinder is leaking and the brake lining
material is saturated with brake fluid, the brake
shoes must be replaced.
ADJUSTMENTS
BRAKE LAMP SWITCH
(1) Depress and hold the brake pedal while rotat-
ing the brake lamp switch (Fig. 125) in a counter-
clockwise direction approximately 30 degrees.
(2) Pull the switch rearward and remove it from
its mounting bracket.
(3) If necessary, disconnect the wiring harness con-
nector from the switch.
(4) Hold the brake lamp switch firmly in one hand.
Using the other hand, pull outward on the plunger of
the switch until it has ratcheted out to its fully
extended position.
(5) If disconnected, connect the wiring harness
connector to the stop lamp switch.(6) Mount the brake lamp switch into the bracket
using the following procedure:
²Depress the brake pedal as far down as possible.
²Install the switch in its bracket by aligning the
index tab on the switch with the slot in the mounting
bracket.
²When the switch is fully seated in its bracket,
rotate the switch clockwise approximately 30É to lock
the switch into place.
CAUTION: Do not use excessive force when pulling
back on the brake pedal to adjust the brake lamp
switch. If too much force is used, the switch or
striker can be damaged.
(7) Gently pull back on the brake pedal until the
pedal stops moving. This will ratchet the switch
plunger backward to the correct adjustment position.
(8) Check the stop lamps to verify that they are
operating properly and not staying on when the
pedal is in the released position.
DRUM BRAKE SHOES
(1) Verify the parking brake lever is in the fully
released position.
(2) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group fro the
proper lifting procedure.
(3) Remove the rear brake adjusting hole rubber
plug from the rear brake shoe support plate (Fig.
126).
Fig. 125 Brake Lamp Switch
1 ± SWITCH
2 ± CLIP
3 ± BRAKE PEDAL
4 ± CONNECTOR
Fig. 126 Rear Brake Adjusting Hole Plug
1 ± REAR BRAKE SUPPORT PLATE
2 ± REAR STRUT
3 ± BRAKE ADJUSTING HOLE PLUG
PLBRAKES 5 - 61
CLEANING AND INSPECTION (Continued)
Page 141 of 1285

(4) Insert a brake adjustment tool, or a screw-
driver, through the adjusting hole in support plate
and against the star wheel of the adjuster screw.
Move the handle of tool downward to adjust the
brake drag. Rotate the tire and wheel assembly while
adjusting the adjuster screw. Continue to adjust the
shoes until a slight drag is noticed when the tire and
wheel assembly is rotated.
NOTE: In the event the brake shoes are over-ad-
justed, the adjuster can be backed off using the fol-
lowing step. If not, proceed to step 6.
(5) If the shoes are in the over-adjusted position,
insert a thin screwdriver into brake adjusting hole
and push back the adjusting lever out of engagement
with star wheel (Fig. 127). Take care not to bend the
adjusting lever. While holding the adjusting lever out
of engagement with star wheel, back off the star
wheel until the tire and wheel assembly is free to
turn without dragging. Repeat the adjustment proce-
dure.
(6) Install adjusting hole rubber plug (Fig. 126).
(7) Repeat the above adjustment procedure to the
other side brakes.
(8) Apply and release the park brake lever one
time after the adjustment process is completed so the
parking brakes can readjust themselves to the new
brake shoe adjustment.
PARKING BRAKE SHOES (REAR DISC BRAKES)
NOTE: The parking brake shoes used in the drum-
in-hat park brake system do not automatically
adjust to compensate for brake shoe lining wear.Therefore, it is necessary to manually adjust the
parking brake shoes.
(1) Verify the parking brake lever is in the
released position.
(2) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(3) Remove the rubber plug from the adjusting
hole in the disc brake caliper adapter.
(4) Adjust the parking brakes. Use the first bullet
point for the adjustment of the left side parking
brake shoes. Use the second bullet point for the
adjustment of the right side parking brake shoes.
²Insert a medium size screwdriver through
adjustment hole in the left backing plate. Position
the screwdriver against the star wheel on the park-
ing brake shoe adjuster. Using the screwdriver,
rotate the star wheel downward until a slight drag is
noticed when turning the rear tire and wheel assem-
bly. Then, using the screwdriver, slowly rotate the
star wheel upward, backing off the adjuster, just
enough to allow the rear tire and wheel assembly to
rotate without the parking brake shoes dragging. Do
not back off the adjuster star wheel more than two
clicks past the point of no drag. The parking brake
shoe-to-drum clearance is now properly set.
²Insert a medium size screwdriver through
adjustment hole in the right backing plate. Position
the screwdriver against the star wheel on the park-
ing brake shoe adjuster. Using the screwdriver,
rotate the star wheel upward until a slight drag is
noticed when turning the rear tire and wheel assem-
bly. Then, using the screwdriver, slowly rotate the
star wheel downward, backing off the adjuster, just
enough to allow the rear tire and wheel assembly to
rotate without the parking brake shoes dragging. Do
not back off the adjuster star wheel more that two
clicks past the point of no drag. The parking brake
shoe-to-drum clearance is now properly set.
(5) Install the rubber plug in the adjusting holes of
the disc brake caliper adapter.
(6) Lower the vehicle until the rear tires are just
clearing the floor.
(7) Reach inside the vehicle and fully apply and
release the park brakes two times after adjusting the
parking brake shoes.
(8) With the parking brake lever in the fully
applied position, attempt to hand rotate each rear
tire and wheel assembly to ensure that the parking
brake shoes are working.
(9) With the parking brake lever in the released
position, hand rotate each rear tire and wheel assem-
bly to ensure that the parking brake shoes are not
dragging.
Fig. 127 Backing Off Brake Adjuster Screw
1 ± MEDIUM SCREWDRIVER
2 ± BRAKE ADJUSTING HOLE
3 ± THIN SCREWDRIVER OR WELDING ROD
5 - 62 BRAKESPL
ADJUSTMENTS (Continued)
Page 142 of 1285

SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 3 specifications and SAE J1703 standards.
No other type of brake fluid is recommended or
approved for usage in the vehicle brake system. Use
only Mopar brake fluid or an equivalent from a
tightly sealed container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. An
open container will absorb moisture from the air
and contaminate the fluid.
CAUTION: Never use any type of a petroleum-
based fluid in the brake hydraulic system. Use of
such type fluids will result in seal damage of the
vehicle brake hydraulic system causing a failure of
the vehicle brake system. Petroleum based fluids
would be items such as engine oil, transmission
fluid, power steering fluid, etc.
BRAKE ACTUATION SYSTEM
ACTUATION:
Vacuum Operated Power Brakes.....Standard
Hydraulic System.......Dual-Diagonally Split
BRAKE PEDAL:
Pedal Ratio..........................3.41
POWER BRAKE BOOSTER:
Make/Type..................Bosch/Vacuum
Mounting Studs.................. M8x1.25
Diaphragm Size/Type........ 205mmTandem
MASTER CYLINDER ASSEMBLY:
Type ........................Dual Tandem
Body Material...........Anodized Aluminum
Reservoir Material.............Polypropelene
MASTER CYLINDER BORE STROKE AND
SPLIT:
NonABS ..............22.23 mm x 34.0 mm
(0.875 in. x 1.34 in.)
ABS . . 23.82 mm x 34.0 mm (0.937 in. x 1.34 in.)
Displacement Split.................. 50/50MASTER CYLINDER FLUID OUTLET PORTS:
Tube Fitting Type...... SAE45ÉInverted Flare
W/ABS - Primary Tube Nut
Thread........................7/16 in.±24
W/ABS - Secondary Tube Nut
Thread........................ 3/8in.±24
W/O ABS - All Tube Nut Threads....7/16 in.±24
ABS HYDRAULIC CONTROL UNIT:
Hydraulic Tube Fitting
Type................ SAE45ÉInverted Flare
All Tube Nut Threads............7/16 in.±24
PROPORTIONING VALVE:
Material.......................Aluminum
Function.....Hydraulic Pressure Proportioning
BRAKE FASTENER TORQUE SPECIFICATIONS
DESCRIPTION TORQUE
BRAKE TUBES:
Tube Nuts............... 17N´m(145 in. lbs.)
MASTER CYLINDER:
Mounting Nuts.......... 28N´m(250 in. lbs.)
POWER BRAKE BOOSTER:
Mounting Nuts.......... 34N´m(300 in. lbs.)
DISC BRAKE CALIPER:
Caliper Banjo Bolt......... 48N´m(35ft.lbs.)
Guide Pin Bolts.......... 22N´m(192 in. lbs.)
Bleeder Screw........... 15N´m(125 in. lbs.)
WHEEL CYLINDER (REAR):
Mounting Bolts.......... 13N´m(115in.lbs.)
Bleeder Screw............ 10N´m(80in.lbs.)
DRUM BRAKE SHOE SUPPORT PLATE
(REAR):
Mounting Bolts........... 75N´m(55ft.lbs.)
DISC BRAKE ADAPTER (REAR):
Mounting Bolts........... 75N´m(55ft.lbs.)
HUB AND BEARING (REAR):
Retaining Nut.......... 217N´m(160 ft. lbs.)
PARKING BRAKE:
Lever Mounting Nuts..... 28N´m(250 in. lbs.)
TIRE AND WHEEL:
Wheel Mounting Nut...........109±150 N´m
(80±110 ft. lbs.)
INTEGRATED CONTROL UNIT:
Mounting Bolts........... 11N´m(97in.lbs.)
CAB Mounting bolts........ 2N´m(17in.lbs.)
Bracket-to-Frame Rail Bolts.......... 23N´m
(200 in. lbs.)
WHEEL SPEED SENSOR:
Head Mounting bolt...... 12N´m(105 in. lbs.)
PLBRAKES 5 - 63
Page 143 of 1285
SPECIAL TOOLS
BASE BRAKE SYSTEM
Adapters, Brake Pressure 6805
Adapter, Brake Pressure 8644
Gauge Set C-4007-A
Handle, Universal C-4171
Installer, Dust Boot C-4689
Dial Indicator C-3339
Tubes, Master Cylinder Bleed 8358
5 - 64 BRAKESPL
Page 144 of 1285

ANTILOCK BRAKE SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM OPERATION......65
ANTILOCK BRAKE SYSTEM COMPONENTS....66
ELECTRONIC BRAKE DISTRIBUTION.........69
TRACTION CONTROL SYSTEM..............70
HYDRAULIC CIRCUITS AND VALVE
OPERATION...........................71
DIAGNOSIS AND TESTING
SERVICE WARNINGS AND CAUTIONS........74
ABS GENERAL DIAGNOSTICS INFORMATION . . 74
ABS WIRING DIAGRAM INFORMATION........74
ABS VEHICLE TEST DRIVE.................74
ABS ELECTRONIC DIAGNOSIS..............75
TONE WHEEL...........................76
BRAKE FLUID CONTAMINATION.............76
SERVICE PROCEDURES
BRAKE FLUID LEVEL CHECKING............77ANTILOCK BRAKE SYSTEM BLEEDING.......77
MASTER CYLINDER BLEEDING.............77
REMOVAL AND INSTALLATION
SERVICE WARNINGS AND CAUTIONS........78
MASTER CYLINDER......................78
INTEGRATED CONTROL UNIT...............79
WHEEL SPEED SENSOR (FRONT)...........81
WHEEL SPEED SENSOR (REAR)............83
DISASSEMBLY AND ASSEMBLY
INTEGRATED CONTROL UNIT...............84
SPECIFICATIONS
TONE WHEEL RUNOUT....................85
WHEEL SPEED SENSOR-TO-TONE WHEEL
CLEARANCE...........................85
BRAKE FASTENER TORQUE
SPECIFICATIONS.......................85
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM OPERATION
This section covers the physical and operational
descriptions, and the on-car service procedures for
the Mark 20e Antilock Brake System (ABS) with
traction control. It is the only antilock brake system
available on this vehicle.
The purpose of the antilock brake system is to pre-
vent wheel lockup under braking conditions on virtu-
ally 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.
The traction control system reduces wheel slip and
maintains traction at the driving speeds below 56
kph (35 mph) when road conditions call for traction
assistance. Refer to TRACTION CONTROL SYSTEM
in this section for more information.
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking
when the brakes are applied in the partial braking
range. Refer to ELECTRONIC BRAKE DISTRIBU-
TION in this section for more information.
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-
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 four control channels.
During antilock operation of the vehicle's brake sys-
tem, the wheels are controlled independently and are
on separate control channels.
The system can build, hold 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).
PLBRAKES 5 - 65