warning DODGE TOWN AND COUNTRY 2001 Owner's Manual

REMOVAL - FRONT DISC BRAKE SHOES
(DISC/DRUM BRAKES)
(1) Raise the vehicle. Refer to HOISTING in
LUBRICATION AND MAINTENANCE.
NOTE: Perform Step 2 through Step 5 on each side
of the vehicle.
(2) Remove the front tire and wheel assembly.
(3) Remove the two brake caliper guide pin bolts
(Fig. 14).
(4) Remove the disc brake caliper from the disc
brake adapter and hang out of the way using wire or
a bungee cord. Use care not to overextend the brake
hose when doing this.
(5) Remove the brake shoes from the disc brake
caliper adapter.
CLEANING - DISC BRAKE SHOES
WARNING: DUST AND DIRT ACCUMULATING ON
BRAKE PARTS DURING NORMAL USE MAY CON-
TAIN ASBESTOS FIBERS FROM PRODUCTION OR
AFTERMARKET BRAKE LININGS. BREATHING
EXCESSIVE CONCENTRATIONS OF ASBESTOS
FIBERS CAN CAUSE SERIOUS BODILY HARM.
EXERCISE CARE WHEN SERVICING BRAKE
PARTS. DO NOT SAND OR GRIND BRAKE LINING
UNLESS EQUIPMENT USED IS DESIGNED TO CON-
TAIN THE DUST RESIDUE. DO NOT CLEAN BRAKE
PARTS WITH COMPRESSED AIR OR BY DRY
BRUSHING. CLEANING SHOULD BE DONE BY
DAMPENING THE BRAKE COMPONENTS WITH AFINE MIST OF WATER, THEN WIPING THE BRAKE
COMPONENTS CLEAN WITH A DAMPENED CLOTH.
DISPOSE OF CLOTH AND ALL RESIDUE CONTAIN-
ING ASBESTOS FIBERS IN AN IMPERMEABLE
CONTAINER WITH THE APPROPRIATE LABEL. FOL-
LOW PRACTICES PRESCRIBED BY THE OCCUPA-
TIONAL SAFETY AND HEALTH ADMINISTRATION
(OSHA) AND THE ENVIRONMENTAL PROTECTION
AGENCY (EPA) FOR THE HANDLING, PROCESSING,
AND DISPOSING OF DUST OR DEBRIS THAT MAY
CONTAIN ASBESTOS FIBERS.
INSPECTION - DISC BRAKE SHOES
Visually inspect brake shoes (pads) for uneven lin-
ing wear. Also inspect for excessive lining deteriora-
tion. Check the clearance between the tips of the
wear indicators on the shoes (if equipped) and the
brake rotors.
If a visual inspection does not adequately deter-
mine the condition of the lining, a physical check will
be necessary. To check the amount of lining wear,
remove the disc brake shoes from the calipers.
Measure each brake shoe. The combined brake
shoe and its lining material thickness should be mea-
sured at its thinnest point.
²For front disc brake shoes, when a set of brake
shoes are worn to a thickness of approximately 7.95
mm (5/16 inch), they should be replaced.
²For rear disc brake shoes, when a set of brake
shoes are worn to a thickness of approximately 7.0
mm (9/32 inch), they should be replaced.
Replacebothdisc brake shoes (inboard and out-
board) on each caliper. It is necessary to replace the
Fig. 13 Removing Inboard Shoe
1 - INBOARD BRAKE SHOE
2 - HANGER WIRE
3 - CALIPER ASSEMBLY
4 - RETAINING CLIP
5 - PISTON
Fig. 14 Brake Caliper Mounting (Typical)
1 - BRAKE HOSE
2 - ADAPTER MOUNTING BOLTS
3 - BANJO BOLT
4 - CALIPER GUIDE PIN BOLTS
5 - 14 BRAKES - BASERS
BRAKE PADS/SHOES - FRONT (Continued)
ProCarManuals.com

CLEANING - DISC BRAKE SHOES
WARNING: DUST AND DIRT ACCUMULATING ON
BRAKE PARTS DURING NORMAL USE MAY CON-
TAIN ASBESTOS FIBERS FROM PRODUCTION OR
AFTERMARKET BRAKE LININGS. BREATHING
EXCESSIVE CONCENTRATIONS OF ASBESTOS
FIBERS CAN CAUSE SERIOUS BODILY HARM.
EXERCISE CARE WHEN SERVICING BRAKE
PARTS. DO NOT SAND OR GRIND BRAKE LINING
UNLESS EQUIPMENT USED IS DESIGNED TO CON-
TAIN THE DUST RESIDUE. DO NOT CLEAN BRAKE
PARTS WITH COMPRESSED AIR OR BY DRY
BRUSHING. CLEANING SHOULD BE DONE BY
DAMPENING THE BRAKE COMPONENTS WITH A
FINE MIST OF WATER, THEN WIPING THE BRAKE
COMPONENTS CLEAN WITH A DAMPENED CLOTH.
DISPOSE OF CLOTH AND ALL RESIDUE CONTAIN-
ING ASBESTOS FIBERS IN AN IMPERMEABLE
CONTAINER WITH THE APPROPRIATE LABEL. FOL-
LOW PRACTICES PRESCRIBED BY THE OCCUPA-
TIONAL SAFETY AND HEALTH ADMINISTRATION
(OSHA) AND THE ENVIRONMENTAL PROTECTION
AGENCY (EPA) FOR THE HANDLING, PROCESSING,
AND DISPOSING OF DUST OR DEBRIS THAT MAY
CONTAIN ASBESTOS FIBERS.
INSPECTION - DISC BRAKE SHOES
Visually inspect brake shoes (pads) for uneven lin-
ing wear. Also inspect for excessive lining deteriora-
tion. Check the clearance between the tips of the
wear indicators on the shoes (if equipped) and the
brake rotors.
If a visual inspection does not adequately deter-
mine the condition of the lining, a physical check will
be necessary. To check the amount of lining wear,
remove the disc brake shoes from the calipers.
Measure each brake shoe. The combined brake
shoe and its lining material thickness should be mea-
sured at its thinnest point.
²For front disc brake shoes, when a set of brake
shoes are worn to a thickness of approximately 7.95
mm (5/16 inch), they should be replaced.
²For rear disc brake shoes, when a set of brake
shoes are worn to a thickness of approximately 7.0
mm (9/32 inch), they should be replaced.
Replacebothdisc brake shoes (inboard and out-
board) on each caliper. It is necessary to replace the
shoes on the opposite side of the vehicle as well as
the shoes failing inspection.
If the brake shoe assemblies do not require
replacement, be sure to reinstall the brake shoes in
the original position they were remove from.
INSTALLATION - REAR DISC BRAKE SHOES
(1) Completely retract caliper piston back into pis-
ton bore of caliper assembly.
(2) Lubricate both adapter abutments where the
shoes contact with a liberal amount of MopartMul-
tipurpose Lubricant, or equivalent.
(3) If removed, install the brake rotor on the hub,
making sure it is squarely seated on the face of the
hub.
(4) Install the inboard brake shoe into the caliper
piston by firmly pressing it into the piston bore using
your thumbs. Be sure inboard brake shoe is posi-
tioned squarely against the face of the caliper piston.
(5) Install the outboard brake shoe on the disc
brake caliper. Be sure the outboard shoe is positioned
squarely against the outboard fingers of the caliper.
CAUTION: Use care when installing the caliper
assembly onto the adapter, so the caliper guide pin
bushings do not get damaged by the mounting
bosses.
(6) Carefully lower caliper and brake shoes over
rotor and onto adapter, reversing the removal proce-
dure (Fig. 16).
CAUTION: When installing the caliper guide pin
bolts extreme caution should be taken not to
crossthread the guide pin bolts.
(7) Install the caliper guide pin bolts. Tighten the
guide pin bolts to a torque of 35 N´m (26 ft. lbs.).
(8) Install the wheel and tire assembly. Tighten
the wheel mounting nuts in proper sequence until all
nuts are torqued to half specification. Then repeat
the tightening sequence to the full specified torque of
135 N´m (100 ft. lbs.).
(9) Remove jackstands or lower hoist.
CAUTION: Before moving vehicle, pump the brake
pedal several times to insure the vehicle has a firm
brake pedal to adequately stop the vehicle.
(10) Pump brake pedal several times to set brake
shoes to rotors.
(11) Check fluid level in reservoir.
(12) Road test the vehicle and make several stops
to wear off any foreign material on the brakes and to
seat the brake shoe linings.
RSBRAKES - BASE5-17
BRAKE PADS/SHOES - REAR DISC (Continued)
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DISASSEMBLY - CALIPER GUIDE PIN
BUSHINGS (DISC/DISC BRAKES)
Before disassembling the brake caliper, clean and
inspect it. Refer to CLEANING or INSPECTION in
this section.
(1) Using your fingers, collapse one side of the rub-
ber guide pin bushing. Pull the guide pin bushing out
the other side of the brake caliper mounting boss.
(2) Repeat this procedure on the remaining bush-
ing.
DISASSEMBLY - CALIPER PISTON AND SEAL
WARNING: UNDER NO CONDITION SHOULD HIGH
PRESSURE AIR EVER BE USED TO REMOVE A PIS-
TON FROM A CALIPER BORE. PERSONAL INJURY
COULD RESULT FROM SUCH A PRACTICE.
NOTE: Before disassembling the brake caliper,
clean and inspect it. Refer to CLEANING AND
INSPECTION in this section.
NOTE: The safest way to remove the piston from
the caliper bore is to use the hydraulic pressure of
the vehicle's brake system.
(1) Following the removal procedure in DISC
BRAKE SHOES found in this section, remove the
caliper from the brake rotor and hang the assembly
on a wire hook away from rotor and body of the vehi-
cle so brake fluid cannot get on these components.
Remove the brake shoes, and place a small piece of
wood between the piston and caliper fingers.
(2) Carefully depress the brake pedal to hydrauli-
cally push piston out of its bore. Once completed,
apply and hold down the brake pedal to any position
beyond the first inch of pedal travel using a brake
pedal holding tool. This will prevent the fluid in the
master cylinder reservoir from completely draining
out.
(3) Disconnect the brake fluid flex hose from the
caliper assembly and remove it from the vehicle.
CAUTION: Do not use excessive force when clamp-
ing caliper in vise. Excessive vise pressure will
cause bore distortion.(4) Mount the caliper in a vise equipped with pro-
tective jaws.
(5) Remove the piston dust boot from the caliper
and discard.
NOTE: Do not use a screw driver or other metal tool
for seal removal. Using such tools can scratch the
bore or leave burrs on the seal groove edges.
(6) Using a soft tool such as a plastic trim stick,
work the piston seal out of its groove in caliper pis-
ton bore (Fig. 33). Discard the old seal.
(7) Clean the piston bore and drilled passage ways
using alcohol or a suitable solvent. Wipe it dry using
only a lint-free cloth.
(8) Inspect the piston bore for scoring or pitting.
Bores that show light scratches or corrosion can usu-
ally be cleared of the light scratches or corrosion
using crocus cloth.
Fig. 33 Removing Piston Seal
1 - PLASTIC TRIM STICK
2 - CALIPER
3 - PISTON SEAL GROOVE
4 - PISTON SEAL
RSBRAKES - BASE5-23
DISC BRAKE CALIPERS - FRONT (Continued)
ProCarManuals.com

CLEANING - CALIPER
WARNING: DUST AND DIRT ACCUMULATING ON
BRAKE PARTS DURING NORMAL USE MAY CON-
TAIN ASBESTOS FIBERS FROM PRODUCTION OR
AFTERMARKET BRAKE LININGS. BREATHING
EXCESSIVE CONCENTRATIONS OF ASBESTOS
FIBERS CAN CAUSE SERIOUS BODILY HARM.
EXERCISE CARE WHEN SERVICING BRAKE
PARTS. DO NOT SAND OR GRIND BRAKE LINING
UNLESS EQUIPMENT USED IS DESIGNED TO CON-
TAIN THE DUST RESIDUE. DO NOT CLEAN BRAKE
PARTS WITH COMPRESSED AIR OR BY DRY
BRUSHING. CLEANING SHOULD BE DONE BY
DAMPENING THE BRAKE COMPONENTS WITH A
FINE MIST OF WATER, THEN WIPING THE BRAKE
COMPONENTS CLEAN WITH A DAMPENED CLOTH.
DISPOSE OF CLOTH AND ALL RESIDUE CONTAIN-
ING ASBESTOS FIBERS IN AN IMPERMEABLE
CONTAINER WITH THE APPROPRIATE LABEL. FOL-
LOW PRACTICES PRESCRIBED BY THE OCCUPA-
TIONAL SAFETY AND HEALTH ADMINISTRATION
(OSHA) AND THE ENVIRONMENTAL PROTECTION
AGENCY (EPA) FOR THE HANDLING, PROCESSING,
AND DISPOSING OF DUST OR DEBRIS THAT MAY
CONTAIN ASBESTOS FIBERS.
To clean or flush the internal passages of the brake
caliper, use fresh brake fluid or MopartNon-Chlori-
nated Brake Parts Cleaner. Never use gasoline, ker-
osene, alcohol, oil, transmission fluid or any fluid
containing mineral oil to clean the caliper. These flu-
ids will damage rubber cups and seals.
INSPECTION - CALIPER
Inspect the disc brake caliper for the following:
²Brake fluid leaks in and around boot area and
inboard lining
²Ruptures, brittleness or damage to the piston
dust boot
²Damaged, dry or brittle guide pin dust boots
If caliper fails inspection, disassemble and recondi-
tion caliper, replacing the seals and dust boots.
ASSEMBLY - CALIPER GUIDE PIN BUSHINGS
(DISC/DISC BRAKES)
(1) Fold the guide pin bushing in half lengthwise.
NOTE: To avoid damage to the bushing, do not use
a sharp object to install the guide pin bushing.
(2) Insert the folded bushing into the caliper
mounting boss using your fingers from the rear of
the caliper.
(3) Unfold the bushing using your fingers or a
wooden dowel until the bushing is fully seated intothe caliper housing. The bushing flanges should be
seated evenly on both sides of the bushing hole.
(4) Lubricate inside surfaces of bushing using
MopartDielectric Grease or equivalent.
(5) Repeat the procedure for remaining bushing.
ASSEMBLY - CALIPER PISTON AND SEAL
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. 34)
using only your clean fingers to seat it.
(2) Coat the new piston boot with clean brake
fluid.
(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.
(4) Install piston into caliper bore pushing it past
the piston seal until it bottoms in the caliper bore
(Fig. 35).
(5) Position the dust boot into the counterbore of
the caliper assembly piston bore.
(6) Using a hammer and Installer, Special Tool
C-4689 or C-4842 (depending on piston size), and
Handle, Special Tool C-4171, drive the boot into the
counterbore of the caliper as necessary (Fig. 36).
Fig. 34 Installing New Piston Seal
1 - CALIPER
2 - PISTON SEAL
3 - SEAL GROOVE
5 - 24 BRAKES - BASERS
DISC BRAKE CALIPERS - FRONT (Continued)
ProCarManuals.com

DISASSEMBLY - CALIPER PISTON AND SEAL
WARNING: UNDER NO CONDITION SHOULD HIGH
PRESSURE AIR EVER BE USED TO REMOVE A PIS-
TON FROM A CALIPER BORE. PERSONAL INJURY
COULD RESULT FROM SUCH A PRACTICE.
NOTE: Before disassembling the brake caliper,
clean and inspect it. Refer to CLEANING AND
INSPECTION in this section.
NOTE: The safest way to remove the piston from
the caliper bore is to use the hydraulic pressure of
the vehicle's brake system.
(1) Following the removal procedure in DISC
BRAKE SHOES found in this section, remove the
caliper from the brake rotor and hang the assembly
on a wire hook away from rotor and body of the vehi-
cle so brake fluid cannot get on these components.
Remove the brake shoes, and place a small piece of
wood between the piston and caliper fingers.
(2) Carefully depress the brake pedal to hydrauli-
cally push piston out of its bore. Once completed,
apply and hold down the brake pedal to any position
beyond the first inch of pedal travel using a brake
pedal holding tool. This will prevent the fluid in the
master cylinder reservoir from completely draining
out.(3) Disconnect the brake fluid flex hose from the
caliper assembly and remove it from the vehicle.
CAUTION: Do not use excessive force when clamp-
ing caliper in vise. Excessive vise pressure will
cause bore distortion.
(4) Mount the caliper in a vise equipped with pro-
tective jaws.
(5) Remove the piston dust boot from the caliper
and discard.
NOTE: Do not use a screw driver or other metal tool
for seal removal. Using such tools can scratch the
bore or leave burrs on the seal groove edges.
(6) Using a soft tool such as a plastic trim stick,
work the piston seal out of its groove in caliper pis-
ton bore (Fig. 39). Discard the old seal.
(7) Clean the piston bore and drilled passage ways
using alcohol or a suitable solvent. Wipe it dry using
only a lint-free cloth.
(8) Inspect the piston bore for scoring or pitting.
Bores that show light scratches or corrosion can usu-
ally be cleared of the light scratches or corrosion
using crocus cloth.
Fig. 38 Removing/Installing Caliper
1 - LIFT THIS END OF CALIPER AWAY FROM ADAPTER FIRST
2 - DISC BRAKE CALIPER
3 - ADAPTER ABUTMENT
4 - OUTBOARD BRAKE SHOE HOLD DOWN CLIP
5 - OUTBOARD BRAKE SHOE
6 - ROTOR
7 - ADAPTER
Fig. 39 Removing Piston Seal
1 - PLASTIC TRIM STICK
2 - CALIPER
3 - PISTON SEAL GROOVE
4 - PISTON SEAL
RSBRAKES - BASE5-27
DISC BRAKE CALIPERS - REAR (Continued)
ProCarManuals.com

CLEANING - CALIPER
WARNING: DUST AND DIRT ACCUMULATING ON
BRAKE PARTS DURING NORMAL USE MAY CON-
TAIN ASBESTOS FIBERS FROM PRODUCTION OR
AFTERMARKET BRAKE LININGS. BREATHING
EXCESSIVE CONCENTRATIONS OF ASBESTOS
FIBERS CAN CAUSE SERIOUS BODILY HARM.
EXERCISE CARE WHEN SERVICING BRAKE
PARTS. DO NOT SAND OR GRIND BRAKE LINING
UNLESS EQUIPMENT USED IS DESIGNED TO CON-
TAIN THE DUST RESIDUE. DO NOT CLEAN BRAKE
PARTS WITH COMPRESSED AIR OR BY DRY
BRUSHING. CLEANING SHOULD BE DONE BY
DAMPENING THE BRAKE COMPONENTS WITH A
FINE MIST OF WATER, THEN WIPING THE BRAKE
COMPONENTS CLEAN WITH A DAMPENED CLOTH.
DISPOSE OF CLOTH AND ALL RESIDUE CONTAIN-
ING ASBESTOS FIBERS IN AN IMPERMEABLE
CONTAINER WITH THE APPROPRIATE LABEL. FOL-
LOW PRACTICES PRESCRIBED BY THE OCCUPA-
TIONAL SAFETY AND HEALTH ADMINISTRATION
(OSHA) AND THE ENVIRONMENTAL PROTECTION
AGENCY (EPA) FOR THE HANDLING, PROCESSING,
AND DISPOSING OF DUST OR DEBRIS THAT MAY
CONTAIN ASBESTOS FIBERS.
To clean or flush the internal passages of the brake
caliper, use fresh brake fluid or MopartNon-Chlori-
nated Brake Parts Cleaner. Never use gasoline, ker-
osene, alcohol, oil, transmission fluid or any fluid
containing mineral oil to clean the caliper. These flu-
ids will damage rubber cups and seals.
INSPECTION - CALIPER
Inspect the disc brake caliper for the following:
²Brake fluid leaks in and around boot area and
inboard lining
²Ruptures, brittleness or damage to the piston
dust boot
²Damaged, dry or brittle guide pin dust boots
If caliper fails inspection, disassemble and recondi-
tion caliper, replacing the seals and dust boots.
ASSEMBLY - CALIPER PISTON AND SEAL
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.
40)using only your clean fingers to seat it.
(2) Coat the new piston boot with clean brake
fluid.
(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.
(4) Install piston into caliper bore pushing it past
the piston seal until it bottoms in the caliper bore
(Fig. 41).
(5) Position the dust boot into the counterbore of
the caliper assembly piston bore.
Fig. 40 Installing New Piston Seal
1 - CALIPER
2 - PISTON SEAL
3 - SEAL GROOVE
Fig. 41 Installing Piston Into Caliper Bore
1 - BOOT
2 - PISTON
3 - CALIPER
5 - 28 BRAKES - BASERS
DISC BRAKE CALIPERS - REAR (Continued)
ProCarManuals.com

(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 link from
park brake mechanism.
(16) Remove the warning lamp ground switch con-
nector from the park brake pedal mechanism (Fig.
79).
(17) Remove front park brake cable button from
park brake pedal mechanism. Tap end housing for
front park brake cable out of park brake pedal mech-
anism.
INSTALLATION
(1) Install park brake cable end housing into park
brake pedal mechanism.
(2) Install cable retainer onto the park brake cable
strand and then install retainer into pedal bracket.
(3) Install cable strand button into the clevis on
the park brake pedal mechanism.
(4) Install wiring harness connector on warning
indicator lamp ground switch.
(5) Install the park brake release rod on the
release mechanism of the park brake pedal.
(6) Position the park brake pedal mechanism into
its installed position on the body of the vehicle.
(7) Loosely install the top bolt mounting the park
brake pedal mechanism to the body (Fig. 79).
(8) Loosely install the forward nut mounting the
park brake pedal mechanism to the body (Fig. 79).
(9) Loosely install the lower bolt mounting the
park brake pedal mechanism to the body (Fig. 79).
(10) Tighten pedal mechanism attaching bolts and
nut to 28 N´m (250 in. lbs.).
(11) Verify that the park brake pedal is in the fully
released (full up) position.
(12) Raise vehicle.
(13) Install the front park brake cable on the park
brake cable equalizer (Fig. 78).
NOTE: If the original lever assembly is being used,
the lever mechanism auto adjuster spring tension
will need to be reset. (Refer to 5 - BRAKES/PARK-
ING BRAKE - STANDARD PROCEDURE)
(14) Lower vehicle.
(15) Remove the lock-out pin (if a new lever has
been installed) from the automatic cable adjuster on
the park brake pedal mechanism.
(16) Install the electrical junction block on the
instrument panel.
(17) Install the reinforcement on the lower instru-
ment panel.
(18) Install the steering column lower cover on the
lower instrument panel.(19) Install the silencer panel under the instru-
ment panel.
(20) Install the left side kick panel.
(21) Install the sill scuff plate on the lower sill of
the left door.
(22) Install the negative (ground) cable on the bat-
tery.
(23) Cycle the park brake pedal one time. This will
seat the park brake cables and will allow the auto-
matic self adjuster to properly tension the park brake
cables.
SHOES - PARKING BRAKE
REMOVAL
(1) Set the parking brake.The parking brake is
set to keep the hub/bearing and axle shaft from
rotating when loosening the hub nut.
(2) Raise vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
(3) Remove the wheel and tire assembly.
(4) Remove the cotter pin and nut retainer (Fig.
80) from the stub shaft of the outer C/V joint.
(5) Remove the spring washer (Fig. 81) from the
stub shaft of the outer C/V joint.
(6) Remove the hub nut and washer (Fig. 82) from
the stub shaft of the outer C/V joint.
(7) Release the parking brake.
Fig. 80 Cotter Pin And Nut Retainer
1 - CALIPER
2 - COTTER PIN
3 - ROTOR
4 - NUT RETAINER
5 - OUTER C/V JOINT
RSBRAKES - BASE5-53
LEVER (Continued)
ProCarManuals.com

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
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BRAKES - ABS (Continued)
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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)
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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.
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BRAKES - ABS (Continued)
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