lock CHRYSLER CARAVAN 2002 Manual PDF

(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. 114).
(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.
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. 118).
(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.
ADJUSTMENTS
ADJUSTMENT - PARKING BRAKE 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.
CABLES - PARKING BRAKE
(EXPORT)
REMOVAL - FRONT CABLE
(Refer to 5 - BRAKES - BASE/PARKING BRAKE/
LEVER - REMOVAL)
INSTALLATION - FRONT CABLE
(Refer to 5 - BRAKES - BASE/PARKING BRAKE/
LEVER - INSTALLATION)
LEVER - PARKING BRAKE
REMOVAL
(1) Manually release the automatic self-adjusting
mechanism tension of the parking brake lever (pedal)
assembly. (Refer to 5 - BRAKES/PARKING BRAKE -
STANDARD PROCEDURE).
(2) Disconnect negative (ground) cable from the
battery and isolate cable from battery terminal.
5 - 72 BRAKES - BASERS
CABLES - PARKING BRAKE (Continued)
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(3) Remove sill scuff plate from left door sill.
(4) Remove the left side kick panel.
(5) Remove the silencer panel under the instru-
ment panel.
(6) Remove the steering column cover from the
lower instrument panel.
(7) Remove the reinforcement from the lower
instrument panel.
(8) Remove the front parking brake cable from the
parking brake cable equalizer (Fig. 121).
(9) Remove tension from front park brake cable.
Tension is removed by releasing the locking pliers
from the front park brake cable.
(10) Remove the 3 bolts mounting the wiring junc-
tion block to the instrument panel.
NOTE: When removing the lower mounting bolt,
push the park brake pedal down 5 clicks to access
the lower mounting bolt.
(11) Remove the lower bolt mounting the park
brake pedal to the body (Fig. 122).
(12) Remove the forward nut mounting the park
brake pedal to the body (Fig. 122).
(13) Remove the upper bolt mounting the park
brake pedal to the body (Fig. 122).
(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.
122).(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. 122).
(8) Loosely install the forward nut mounting the
park brake pedal mechanism to the body (Fig. 122).
(9) Loosely install the lower bolt mounting the
park brake pedal mechanism to the body (Fig. 122).
(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. 121).
Fig. 121 Parking Brake Cable Equalizer
1 - EQUALIZER
2 - LEFT REAR PARKING BRAKE CABLE
3 - LOCKING NUT
4 - INTERMEDIATE PARKING BRAKE CABLE
5 - FRONT PARKING BRAKE CABLE
Fig. 122 PARKING BRAKE LEVER MOUNTING
1 - WIRE HARNESS CONNECTOR
2 - LEVER MECHANISM
3 - FRONT CABLE
RSBRAKES - BASE5-73
LEVER - PARKING BRAKE (Continued)
ProCarManuals.com

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.
LEVER - PARKING BRAKE
(EXPORT)
REMOVAL - PARKING BRAKE LEVER AND
FRONT CABLE
(1)Raise vehicle. (Refer to LUBRICATION & MAIN-
TENANCE/HOISTING - STANDARD PROCEDURE)
(2) Grasp the exposed section of the front parking
brake cable and pull rearward on it. While holding
the park brake in this position, install a pair of lock-
ing pliers on the front parking brake cable just rear-
ward of the second body outrigger bracket (Fig. 123).
(3) Remove the left rear and intermediate parking
brake cables from the parking brake cable equalizer
(Fig. 124).
(4) Remove the equalizer from the front parking
brake cable.
(5) Remove the locking pliers from the front park-
ing brake cable. This will allow the adjuster in the
parking brake lever mechanism to rotate around to
its stop and remove the tension from the adjuster
and front park brake cable.
(6) Remove the front parking brake cable housing
from body outrigger bracket. Cable is removable by
sliding a 14 mm box wrench over the cable retainer
and compressing the three retaining fingers.Alter-
nate method:Use an aircraft type hose clamp and
screwdriver.(7) Remove the four mounting nuts from the bot-
tom of the parking brake lever bracket.
(8) Lower vehicle.
(9) Remove the floor console. (Refer to 23 - BODY/
INTERIOR/FLOOR CONSOLE - REMOVAL)
(10) If equipped with a manual transaxle, remove
the gearshift mechanism. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/MANUAL/SHIFT MECHANISM
- REMOVAL)
(11) Unhook the end of the parking brake cable
from the lever mechanism.
Fig. 123 Locking Out Automatic Adjuster
1 - PARK BRAKE CABLE
2 - REAR BODY OUTRIGGER BRACKET
3 - LOCKING PLIERS
Fig. 124 Parking Brake Cable Equalizer
1 - EQUALIZER
2 - LEFT REAR PARKING BRAKE CABLE
3 - LOCKING NUT
4 - INTERMEDIATE PARKING BRAKE CABLE
5 - FRONT PARKING BRAKE CABLE
5 - 74 BRAKES - BASERS
LEVER - PARKING BRAKE (Continued)
ProCarManuals.com

(12) Compress the parking brake cable retainer by
sliding a 14 mm wrench over the cable retainer and
compress the three (3) retaining fingers.
(13) Remove the three screws from the parking
brake grommet on the floor pan of the passenger
compartment.
(14) Lift the parking brake lever and slide the
parking brake cable out.
(15) Pull the cable through the floor pan from
inside the vehicle.
INSTALLATION - PARKING BRAKE LEVER AND
FRONT CABLE
(1) Pass the parking brake cable down through the
hole in the floor pan from inside of vehicle.
(2) Pass cable end button through the hole in the
lever bracket and press the cable housing into the
hole until all three retaining fingers lock the cable to
the lever bracket.
(3) Hook the end of the parking brake cable on the
parking brake lever mechanism.
(4) Press the cable grommet into the hole in the
floor pan and install the three screws securing it to
the floor pan.
(5) If equipped with a manual transaxle, install
the gearshift mechanism. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/MANUAL/SHIFT MECHANISM
- INSTALLATION)
(6) Install the floor console. (Refer to 23 - BODY/
INTERIOR/FLOOR CONSOLE - INSTALLATION)
(7) Raise the vehicle.
(8) Install the four mounting nuts securing the
parking brake lever bracket in place.
(9) Install the front park cable housing retainer to
the body outrigger bracket. Press the cable housing
into the outrigger hole until all three retaining fin-
gers lock the cable in place.
(10) Grasp the exposed section of the front parking
brake cable and pull rearward on it. While holding
the park brake in this position, install a pair of lock-
ing pliers on the front parking brake cable just rear-
ward of the second body outrigger bracket.
(11) Install the equalizer on the front parking
brake cable and install the left rear and intermediate
park brake cable in the correct location on the park-
ing brake cable equalizer (Fig. 124).(12) Remove the locking pliers from the front park-
ing brake cable. This will allow the adjuster in the
park brake lever mechanism to tension the parking
brake cables.
(13) Lower the vehicle.
(14) Apply and release the parking brake lever one
time. This will seat the parking brake cables and
allow the auto adjuster in the parking brake lever
mechanism to correctly tension the parking brake
cables.
SHOES - PARKING BRAKE
REMOVAL
(1) AWD only - Set the parking brake.The park-
ing 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) AWD only - Remove the cotter pin and nut
retainer (Fig. 125) from the stub shaft of the outer
C/V joint.
Fig. 125 Cotter Pin And Nut Retainer
1 - CALIPER
2 - COTTER PIN
3 - ROTOR
4 - NUT RETAINER
5 - OUTER C/V JOINT
RSBRAKES - BASE5-75
LEVER - PARKING BRAKE (EXPORT) (Continued)
ProCarManuals.com

(5) AWD only - Remove the spring washer (Fig.
126) from the stub shaft of the outer C/V joint.
(6) AWD only - Remove the hub nut and washer
(Fig. 127) from the stub shaft of the outer C/V joint.
(7) Release the parking brake.
(8) Create slack in the rear park brake cables by
locking the out the automatic adjuster as described.
Grasp the exposed section of front park brake cable
and pull downward on it. Then install a pair of lock-ing pliers on the front park brake cable just rearward
of the second body outrigger bracket (Fig. 128).
(9) Remove the disc brake caliper to adapter guide
pin bolts (Fig. 129).
(10) Remove rear caliper from adapter using the
following procedure. First rotate front of caliper up
from the adapter. Then pull the rear of the caliper
and the outboard brake shoe anti-rattle clip out from
under the rear abutment on the adapter (Fig. 130).
Fig. 126 Spring Washer
1 - HUB NUT
2 - STUB SHAFT
3 - ROTOR
4 - SPRING WASHER
Fig. 127 Hub Nut And Washer
1 - CALIPER
2 - HUB NUT
3 - WASHER
4 - ROTOR
5 - ADAPTER
Fig. 128 Locking Out Automatic Adjuster
1 - PARK BRAKE CABLE
2 - REAR BODY OUTRIGGER BRACKET
3 - LOCKING PLIERS
Fig. 129 Removing Caliper Guide Pin Bolts
1 - DISC BRAKE CALIPER
2 - ADAPTER
3 - AXLE
4 - GUIDE PIN BOLTS
5 - DRIVESHAFT (AWD MODELS ONLY)
5 - 76 BRAKES - BASERS
SHOES - PARKING BRAKE (Continued)
ProCarManuals.com

(11) Support caliper to prevent the weight of the
caliper from damaging the flexible brake hose (Fig.
131).
(12) Remove the rotor from the hub/bearing.
(13) Remove the park brake cable mounting bolt to
adapter.
(14) Remove the end of the park brake cable from
the actuator lever on the adapter (Fig. 132).(15) Remove the end of the park brake cable from
the adapter. Park brake cable is removed from
adapter using a 1/2 wrench slipped over the park
brake cable retainer as show in (Fig. 133) to com-
press the locking tabs on the park brake cable
retainer.
Fig. 130 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. 131 Correctly Supported Caliper
1 - WIRE
2 - CALIPER
3 - ADAPTER
4 - ROTOR
5 - INNER FENDER
Fig. 132 Park Brake Cable Attachment To Actuator
1 - ADAPTER
2 - PARK BRAKE CABLE
3 - ACTUATOR
4 - AXLE
5 - DRIVESHAFT
6 - PARK BRAKE CABLE RETAINER
7 - HORSESHOE CLIP
Fig. 133 Park Brake Cable Removal From Adapter
1 - DRIVESHAFT
2 - 1/2º WRENCH
3 - PARK BRAKE CABLE
4 - PARK BRAKE CABLE RETAINER
5 - ADAPTER
RSBRAKES - BASE5-77
SHOES - PARKING BRAKE (Continued)
ProCarManuals.com

(11) Install the hub/bearing on the stub shaft of
outer C/V joint (AWD only) and into the end of the
axle. (Fig. 137).
(12) In a progressive crisscross pattern, tighten
the 4 hub/bearing mounting bolts until the hub/bear-
ing is squarely seated against the axle. Then tighten
the hub/bearing mounting bolts to a torque of 129
N´m (95 ft. lbs.).
(13) AWD only - Install the wheel speed sensor on
the hub/bearing and adapter. Install the wheel speed
sensor attaching bolt (Fig. 134). Tighten the wheel
speed sensor attaching bolt to a torque of 12 N´m
(105 in. lbs).
(14) FWD only - Install the wheel speed sensor in
the following fashion:
(a) If metal wheel speed sensor retaining clip is
not in the neutral installed position on hub and
bearing cap, install from the bottom, if necessary,
and push clip upward until it snaps into position.
(b) Install wheel speed sensor head into rear of
hub and bearing aligning index tab with the notch
in the top of the mounting hole. Push the sensor in
until it snaps into place on the metal retaining
clip.
(c) Install secondary (yellow) retaining clip over
wheel speed sensor head and engage the tabs on
each side.(15) Install the park brake cable into its mounting
hole in the adapter.Be sure all the locking tabs
on the park brake cable retainer are expanded
out to ensure the cable will not pull out of the
adapter.
(16) Install the end of the park brake cable on the
park brake actuator lever (Fig. 132).
(17) Attach park brake cable to adapter using
mounting bolt.
(18) Remove the locking pliers (Fig. 128) from the
front park brake cable.
(19) Adjust the park brake drum-in-hat brake
shoes. (Refer to 5 - BRAKES/PARKING BRAKE/
SHOES - ADJUSTMENTS).
(20) Install the rotor on the hub/bearing.
(21) Carefully lower caliper and brake shoes over
rotor and onto the adapter using the reverse proce-
dure for removal (Fig. 130).
CAUTION: When installing guide pin bolts extreme
caution should be taken not to crossthread the cal-
iper guide pin bolts.
(22) Install the caliper guide pin bolts (Fig. 129).
Tighten the guide pin bolts to a torque of 35 N´m (26
ft. lbs.).
(23) AWD only - Clean all foreign material off the
threads of the outer C/V joint stub shaft. Install the
washer and hub nut (Fig. 127) on the stub shaft of
the outer C/V joint.
(24) AWD only - Set the parking brake.
(25) AWD only - Tighten the hub nut to a torque of
244 N´m (180 ft. lbs.).
(26) AWD only - Install the spring washer (Fig.
126) on the stub shaft of the outer C/V joint.
(27) AWD only - Install the nut retainer and cotter
pin (Fig. 125) on the stub shaft of the outer C/V joint.
(28) Install the wheel and tire assembly. Tighten
the wheel mounting stud 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.).
(29) Lower vehicle.
(30) Fully apply and release the park brake pedal
one time. This will seat and correctly adjust the park
brake cables.
CAUTION: Before moving vehicle, pump the brake
pedal several times to insure the vehicle has a firm
brake pedal to adequately stop vehicle.
(31) Road test the vehicle and make several stops
to wear off any foreign material on the brakes and to
seat the brake shoe linings.
Fig. 146 Adapter Installed On Mounting Bolts (AWD
Shown)
1 - DRIVESHAFT OUTER C/V JOINT
2 - MOUNTING BOLTS
3 - ADAPTER
4 - PARK BRAKE SHOES
5 - MOUNTING BOLTS
5 - 82 BRAKES - BASERS
SHOES - PARKING BRAKE (Continued)
ProCarManuals.com

BRAKES - ABS
TABLE OF CONTENTS
page page
BRAKES - ABS
DESCRIPTION
DESCRIPTION - ANTILOCK BRAKE
SYSTEM............................85
DESCRIPTION - ANTILOCK BRAKE
SYSTEM (EXPORT)....................85
DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING...............86
DESCRIPTION - TRACTION CONTROL
SYSTEM............................86
OPERATION
OPERATION - ANTILOCK BRAKE SYSTEM . . 86
OPERATION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING...............87
OPERATION - TRACTION CONTROL
SYSTEM............................87
CAUTION
CAUTIONS..........................88
STANDARD PROCEDURE - ANTILOCK BRAKE
SYSTEM BLEEDING...................88
SPECIFICATIONS
ABS FASTENER TORQUE...............89
TONE WHEEL RUNOUT................89
WHEEL SPEED SENSOR AIR GAP........89
FRONT WHEEL SPEED SENSOR
REMOVAL.............................89
INSTALLATION.........................89
REAR WHEEL SPEED SENSOR - AWD
REMOVAL.............................90INSTALLATION.........................90
REAR WHEEL SPEED SENSOR - FWD
REMOVAL.............................91
INSTALLATION.........................91
TONE WHEEL
INSPECTION - TONE WHEEL..............92
TRACTION CONTROL SWITCH
DIAGNOSIS AND TESTING - TRACTION
CONTROL SWITCH....................92
HYDRAULIC/MECHANICAL
OPERATION - HYDRAULIC CIRCUITS AND
VALVES .............................93
HCU (HYDRAULIC CONTROL UNIT)
DESCRIPTION.........................99
OPERATION...........................99
ICU (INTEGRATED CONTROL UNIT)
DESCRIPTION........................100
OPERATION..........................100
REMOVAL
REMOVAL - LHD.....................100
REMOVAL - RHD.....................101
DISASSEMBLY - ICU...................103
ASSEMBLY - ICU......................103
INSTALLATION
INSTALLATION - LHD.................104
INSTALLATION - RHD.................105
BRAKES - ABS
DESCRIPTION
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 - ANTILOCK BRAKE SYSTEM
(EXPORT)
Four-wheel disc antilock brakes are standard on all
models. The Mark 20e antilock brake system is used
on all models. Depending on whether the vehicle is a
left-hand drive (LHD) or right-hand drive (RHD)
model, the integrated control unit (ICU) is located in
one of two locations. On LHD models, the ICU is
mounted above the front suspension cradle/cross-
member below the master cylinder. On RHD models,
the ICU is located behind the front suspension cra-
dle/crossmember on the left side of the vehicle.
RSBRAKES - ABS5-85
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DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING
Vehicles equipped with ABS use electronic variable
brake proportioning (EVBP) to balance front-to-rear
braking. The EVBP is used in place of a rear propor-
tioning valve. The EVBP system uses the ABS sys-
tem to control the slip of the rear wheels in partial
braking range. The braking force of the rear wheels
is controlled electronically by using the inlet and out-
let 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
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-
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
5 - 86 BRAKES - ABSRS
BRAKES - ABS (Continued)
ProCarManuals.com

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 VARIABLE BRAKE
PROPORTIONING
Upon entry into EVBP 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
the rear brake pressure, the outlet valve is switched
off and the inlet valve is pulsed. This increases thepressure to the rear brakes. This back-and-forth pro-
cess will continue until the required slip difference is
obtained. At the end of EVBP 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 EVBP will remain functional during many
ABS fault modes. If both the red BRAKE and amber
ABS warning indicators are illuminated, the EVBP
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
RSBRAKES - ABS5-87
BRAKES - ABS (Continued)
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