brakes CHRYSLER VOYAGER 2001 Service Manual

(12) Install the wheel speed sensor on the hub/
bearing and adapter. Install the wheel speed sensor
attaching bolt (Fig. 89). Tighten the wheel speed sen-
sor attaching bolt to a torque of 12 N´m (105 in. lbs).
(13) 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.
(14) Install the end of the park brake cable on the
park brake actuator lever (Fig. 87).
NOTE: The horseshoe clip must be installed and
installed properly when the park brake cable is
installed in the adapter. The purpose of the horse-
shoe clip is to prevent park brake cable retainer
from moving in the adapter. If horseshoe clip is not
installed the park brake cable retainer will rattle in
the adapter.
(15) Install aNEWhorseshoe clip on the park
brake cable retainer (Fig. 87). The horseshoe clip is
installed between the retainer for the park brake
cable and the adapter. Horseshoe clip must be
installed with the curved end of the clip pointing
straight up and the edge of the curved end facing
toward the rear of the vehicle (Fig. 87).
(16) Remove the locking pliers (Fig. 83) from the
front park brake cable.
(17) Adjust the park brake drum-in-hat brake
shoes. (Refer to 5 - BRAKES/PARKING BRAKE/
SHOES - ADJUSTMENTS).
(18) Install the rotor on the hub/bearing.
(19) Carefully lower caliper and brake shoes over
rotor and onto the adapter using the reverse proce-
dure for removal (Fig. 85).
CAUTION: When installing guide pin bolts extreme
caution should be taken not to crossthread the cal-
iper guide pin bolts.
(20) Install the caliper guide pin bolts (Fig. 84).
Tighten the guide pin bolts to a torque of 22 N´m
(192 in. lbs.).
(21) Clean all foreign material off the threads of
the outer C/V joint stub shaft. Install the washer and
hub nut (Fig. 82) on the stub shaft of the outer C/V
joint.
(22) Set the parking brake.
(23) Tighten the hub nut to a torque of 244 N´m
(180 ft. lbs.).
(24) Install the spring washer (Fig. 81) on the stub
shaft of the outer C/V joint.
(25) Install the nut retainer and cotter pin (Fig.
80) on the stub shaft of the outer C/V joint.
(26) Install the wheel and tire assembly. Tighten
the wheel mounting stud nuts in proper sequenceuntil all nuts are torqued to half specification. Then
repeat the tightening sequence to the full specified
torque of 135 N´m (100 ft. lbs.).
(27) Lower vehicle.
(28) 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.
(29) Road test the vehicle and make several stops
to wear off any foreign material on the brakes and to
seat the brake shoe linings.
ADJUSTMENT - PARKING BRAKE SHOES
CAUTION: Before adjusting the park brake shoes be
sure that the park brake pedal is in the fully
released position. If park brake pedal is not in the
fully released position, the park brake shoes can
not be accurately adjusted.
(1) Raise vehicle.
(2) Remove tire and wheel.
(3) Remove disc brake caliper from caliper adapter
(Fig. 100). (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/DISC BRAKE CALIPERS - REMOVAL).
(4) Remove rotor from hub/bearing.
Fig. 100 Disc Brake Caliper
1 - DISC BRAKE CALIPER
2 - ADAPTER
3 - AXLE
4 - GUIDE PIN BOLTS
5 - DRIVESHAFT (AWD MODELS ONLY)
RSBRAKES - BASE5-59
SHOES (Continued)

NOTE: When measuring the brake drum diameter,
the diameter should be measured in the center of
the area in which the park brake shoes contact the
surface of the brake drum.
(5) Using Gauge, Brake Shoe, Special Tool C-3919
or an equivalent,accuratelymeasure the inside
diameter of the park brake drum portion of the rotor
(Fig. 101).
(6) Using a ruler that reads in 64th of an inch,
accurately read the measurement of the inside diam-
eter of the park brake drum from the special tool
(Fig. 102).
(7) Reduce the inside diameter measurement of
the brake drum that was taken using Special Tool
C-3919 by 1/64 of an inch. Reset Gauge, Brake Shoe,
Special Tool C-3919 or the equivalent used, so that
the outside measurement jaws are set to the reduced
measurement (Fig. 103).(8) Place Gauge, Brake Shoe, Special Tool C-3919,
or equivalent over the park brake shoes. The special
tool must be located diagonally across at the top of
one shoe and bottom of opposite shoe (widest point)
of the park brake shoes.
(9) Using the star wheel adjuster, adjust the park
brake shoes until the lining on the park brake shoes
just touches the jaws on the special tool.
(10) Repeat step 8 above and measure shoes in
both directions.
(11) Install brake rotor on hub and bearing.
(12) Rotate rotor to verify that the park brake
shoes are not dragging on the brake drum. If park
brake shoes are dragging, remove rotor and back off
star wheel adjuster one notch and recheck for brake
shoe drag against drum. Continue with the previous
step until brake shoes are not dragging on brake
drum.
(13) Install disc brake caliper on caliper adapter
(Fig. 100). (Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/DISC BRAKE CALIPERS - INSTALLA-
TION).
(14) Install wheel and tire.
(15) Tighten the wheel mounting nuts in the
proper sequence until all nuts are torqued to half the
specified torque. Then repeat the tightening sequence
to the full specified torque of 129 N´m (95 ft. lbs.).
(16) Lower vehicle.
(17) Apply and release the park brake pedal one
time. This will seat and correctly adjust the park
brake cables.
CAUTION: Before moving vehicle, pump brake
pedal several times to ensure the vehicle has a firm
enough pedal to stop the vehicle.
Fig. 101 Measuring Park Brake Drum Diameter
Fig. 102 Reading Park Brake Drum Diameter
1 - SPECIAL TOOL C-3919
2 - RULER
Fig. 103 Setting Gauge To Park Brake Shoe
Measurement
1 - RULER
2 - SPECIAL TOOL C-3919
5 - 60 BRAKES - BASERS
SHOES (Continued)

(18) Road test the vehicle to ensure proper func-
tion of the vehicle's brake system.
CABLES - PARKING BRAKE
REMOVAL - PARKING BRAKE CABLE (FRONT)
(1) Raise vehicle on jackstands or centered on a
hoist. (Refer to LUBRICATION & MAINTENANCE/
HOISTING - STANDARD PROCEDURE).
(2) Manually release the automatic self-adjusting
mechanism tension of the parking brake lever (pedal)
assembly. (Refer to 5 - BRAKES - STANDARD PRO-
CEDURE).
(3) Remove the intermediate and left rear park
brake cable from the park brake cable equalizer (Fig.
104).
(4) Remove the front park cable housing retainer
from body outrigger bracket (Fig. 105). Cable is
removable by sliding a 14 mm box wrench over cable
retainer and compressing the three retaining fingers.
Alternate method is to use an aircraft type hose
clamp and screwdriver.
(5) Lower vehicle.
(6) Remove the left front door sill molding.
(7) Remove the left front kick panel for access to
the park brake cable and park brake pedal assembly.
(8) Lift floor mat for access to park brake cable
and floor pan. Pull the seal and the park brake cable
(Fig. 106) out of the floor pan of vehicle.
(9) Pull parking brake cable strand end forward
and disconnect button from clevis. Tap cable housing
end fitting out of pedal assembly bracket.(10) Remove cable retainer from the parking brake
lever (pedal) assembly bracket.
(11) Pull front parking brake cable assembly out of
vehicle through hole in floor pan.
Fig. 104 Park Brake Cable Attachment To Equalizer
1 - EQUALIZER
2 - LEFT REAR PARKING BRAKE CABLE
3 - LOCKING NUT
4 - INTERMEDIATE PARKING BRAKE CABLE
5 - FRONT PARKING BRAKE CABLE
Fig. 105 Front Park Brake Cable Attachment To
Body
1 - CABLE HOUSING RETAINER
2 - BODY OUTRIGGER BRACKET
3 - PUSH WRENCH OVER END OF RETAINER HERE
4 - FRONT PARK BRAKE CABLE
Fig. 106 Front Park Brake Cable At Floor Pan
1 - PARK BRAKE PEDAL ASSEMBLY
2 - PARK BRAKE PEDAL
3 - CARPET
4 - FRONT PARK BRAKE CABLE
5 - SEAL
6 - FLOOR PAN
RSBRAKES - BASE5-61
SHOES (Continued)

REMOVAL - PARKING BRAKE CABLE
(INTERMEDIATE)
(1) Raise the vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
(2) Manually lock out the automatic self-adjusting
mechanism tension of the parking brake lever (pedal)
assembly. (Refer to 5 - BRAKES - STANDARD PRO-
CEDURE). Once the cable is released from the equal-
izer, do not remove the locking pliers until
reinstallation of the cable is complete.
(3) Remove the intermediate parking brake cable
from the parking brake cable equalizer (Fig. 107).
(4) Remove the locking nut securing the interme-
diate cable housing to the side bracket on the frame
rail (Fig. 107).
(5) Remove the intermediate parking brake cable
from the cable connector attaching it to the right
rear parking brake cable (Fig. 108). Remove the lock-
ing nut securing the intermediate cable housing to
the side bracket on the frame rail (Fig. 108).
(6) If the vehicle is a short-wheel-base model, it
will be necessary to loosen and lower the fuel tank
far enough to remove the intermediate parking brake
cable. (Refer to 14 - FUEL SYSTEM/FUEL DELIV-
ERY/FUEL TANK - REMOVAL).
(7) Remove the intermediate parking brake cable
from the side brackets and vehicle.
REMOVAL - PARKING BRAKE CABLE (RIGHT
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 the rear parking brake cables
by locking out the automatic adjuster as described
here. Grasp an exposed section of front parking
brake cable near the equalizer and pull down on it.
At this time install a pair of locking pliers on the
cable just rearward of the second body outrigger
bracket (Fig. 109).
Fig. 107 Parking Brake Cable Attachment To
Equalizer
1 - EQUALIZER
2 - LEFT REAR PARKING BRAKE CABLE
3 - LOCKING NUT
4 - INTERMEDIATE PARKING BRAKE CABLE
5 - FRONT PARKING BRAKE CABLE
Fig. 108 Intermediate Cable Attachment To Right
1 - RIGHT REAR PARKING BRAKE CABLE
2 - LOCKING NUT
3 - INTERMEDIATE PARKING BRAKE CABLE
Fig. 109 Locking Out Automatic Adjuster
1 - PARK BRAKE CABLE
2 - REAR BODY OUTRIGGER BRACKET
3 - LOCKING PLIERS
5 - 62 BRAKES - BASERS
CABLES (Continued)

(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)

(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)

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)

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)

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

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)