four wheel drive CHRYSLER CARAVAN 2002 User Guide

NOTE: The following wheel sequence should be
used when bleeding the brake hydraulic system.
The use of this wheel sequence will ensure ade-
quate removal of all trapped air from the brake
hydraulic system.
²Left Rear Wheel
²Right Front Wheel
²Right Rear Wheel
²Left Front Wheel
NOTE: When bleeding the brake system, some air
may be trapped in the brake lines or valves far
upstream, as much as ten feet from the bleeder
screw (Fig. 2). Therefore, it is essential to have a
fast flow of a large volume of brake fluid when
bleeding the brakes to ensure all the air gets out.
The brakes may be manually bled or pressure bled.
Refer to the appropriate following procedure.
MANUAL BLEEDING PROCEDURE
NOTE: Correct manual bleeding of the brakes
hydraulic system will require the aid of a helper.
NOTE: To adequately bleed the brakes using the
manual bleeding procedure the rear brakes must be
correctly adjusted. Prior to the manual bleeding of
the brake hydraulic system, correctly adjust the
rear brakes.
(1) Pump the brake pedal three or four times and
hold it down before the bleeder screw is opened.
(2) Push the brake pedal toward the floor and hold
it down. Then open the left rear bleeder screw at
least 1 full turn. When the bleeder screw opens the
brake pedal will drop all the way to the floor.CAUTION: ªJust crackingº the bleeder screw often
restricts fluid flow, allowing only a slow, weak fluid
discharge of fluid. This practice will NOT get all the
air out. Make sure the bleeder is opened at least 1
full turn when bleeding.
(3) Release the brake pedal onlyafterthe bleeder
screw is closed.
(4) Repeat steps 1 through 3, four or five times, at
each bleeder screw in the proper sequence. This
should pass a sufficient amount of fluid to expel all
the trapped air from the brake system. Be sure to
monitor the fluid level in the master cylinder, so it
stays at a proper level so air will not enter the brake
system through the master cylinder.
(5) Check pedal travel. If pedal travel is excessive
or has not been improved, enough fluid has not
passed through the system to expel all the trapped
air. Continue to bleed system as necessary.
(6) Perform a final adjustment of the rear brake
shoes (when applicable), then test drive vehicle to be
sure brakes are operating correctly and that pedal is
solid.
PRESSURE BLEEDING PROCEDURE
CAUTION: Use bleeder tank Special Tool C-3496-B
or equivalent with Adapter, Special Tool 6921, to
pressurize the hydraulic system for bleeding.
Follow pressure bleeder manufacturer's instruc-
tions for use of pressure bleeding equipment.
(1) Install the Adapter Master Cylinder Pressure
Bleed Cap, Special Tool 6921 on the fluid reservoir of
the master cylinder (Fig. 3). Attach the fluid hose
from the pressure bleeder to the fitting on Special
Tool 6921.
(2) Attach a clear plastic hose to the bleeder screw
at one wheel and feed the hose into a clear jar con-
taining fresh brake fluid.
(3) Open the left rear wheel bleeder screw at least
one full turnor more to obtain an adequate flow of
brake fluid.
CAUTION: ªJust crackingº the bleeder screw often
restricts fluid flow, allowing only a slow, weak fluid
discharge of fluid. This practice will NOT get all the
air out. Make sure the bleeder is opened at least 1
full turn when bleeding.
(4) After 4 to 8 ounces of brake fluid has been bled
through the hydraulic system, and an air-free flow is
maintained in the hose and jar, this will indicate a
good bleed of the hydraulic system has been
obtained.
(5) Repeat the procedure at all the other remain-
ing bleeder screws.
Fig. 2 Trapped Air In Brake Fluid Line
1 - TRAPPED AIR
5 - 8 BRAKES - BASERS
BRAKES - BASE (Continued)
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front brakes utilize the familiar internally-vented hat
style rotor. Internally-vented refers to the fact that
the inner most diameter of the braking disc vents to
the inboard side of the rotor (Fig. 16).
CAUTION: TRW and Continental Teves brake rotors
are not interchangeable. If brake rotors are inter-
changed, noise and wear problems can result.
DESCRIPTION - DISC BRAKES (REAR)
There are several distinctive features to the rear
disc brakes on this vehicle (Fig. 17). The single pis-
ton, floating caliper rear disc brake system includes a
hub and bearing assembly, adapter, rotor, caliper, and
brake shoes.
This vehicle is equipped with a caliper having a 42
mm (1.65 in.) piston and uses a 15 inch solid non-
vented brake rotor. The brake rotor is described as a
drum-in-hat style because of its dual role as a brak-
ing disc and parking brake drum.
The parking brake system on vehicles equipped
with rear disc brakes consists of a small duo-servo
drum brake mounted to the caliper adapter and uses
the interior of the rear disc brake rotor as a drum
(hat section of drum-in-hat style brake rotor).
The outboard rear disc brake shoes (pads) are side-
oriented. The shoes are marked indicating which side
they belong on.
DESCRIPTION - DISC BRAKES (EXPORT)
All vehicles are equipped with Four-Wheel-Disc
brakes. Both 15º (BRE) and 16º (BR3) disc/disc brake
systems are available. The disc brakes are manufac-
tured by Continental Teves. The BR3 system is stan-
dard equipment on all-wheel drive and all right-hand
drive models. It is optional on other models.
The BR3 system features larger, externally vented
front brake rotors.
Although there are different disc/disc systems, they
are serviced using the same service procedures. Some
specifications differ.
Fig. 15 ANTI-RATTLE DEVICES ON CALIPERS
1 - CONTINENTAL TEVES CALIPER
2 - TRW CALIPER
3 - ANTI-RATTLE CLIP
4 - ANTI-RATTLE CLIP
Fig. 16 Externally and Internally Vented Rotors
(Cross-Sectional View)
1 - EXTERNAL VENTS (TRW)
2 - INTERNAL VENTS (Continetal Teves)
Fig. 17 Rear Disc Brakes
1 - CALIPER
2 - COTTER PIN
3 - ROTOR
4 - NUT RETAINER
5 - OUTER C/V JOINT
RSBRAKES - BASE5-15
HYDRAULIC/MECHANICAL (Continued)
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CAUTION: Never use any type of a petroleum-based
fluid in the brake hydraulic system. Use of such
type fluids will result in seal damage of the vehicle
brake hydraulic system causing a failure of the
vehicle brake system. Petroleum based fluids would
be items such as engine oil, transmission fluid,
power steering fluid, etc.
JUNCTION BLOCK
DESCRIPTION - NON-ABS JUNCTION BLOCK
A junction block is used on vehicles that are not
equipped with antilock brakes (ABS). The junction
block mounts in the same location as the integrated
control unit (ICU) does on vehicles equipped with
ABS. This allows for use of the same brake tube con-
figuration on all vehicles. The junction block is
located on the driver's side of the front suspension
cradle/crossmember below the master cylinder (Fig.
53).
It has six threaded ports to which the brake tubes
connect. Two are for the primary and secondary
brake tubes coming from the master cylinder. The
remaining four are for the chassis brake tubes going
to each brake assembly.
OPERATION - NON-ABS JUNCTION BLOCK
The junction block distributes the brake fluid com-
ing from the master cylinder primary and secondary
ports to the four chassis brake tubes leading to the
brakes at each wheel. Since the junction block
mounts in the same location as the ABS integrated
control unit (ICU), it allows for the common use of
brake tubes going to the brakes whether the vehicle
is equipped with or without ABS.
NOTE: Although the brake tubes coming from the
master cylinder to the junction block or ABS ICU
may appear to be the same, they are not. They are
unique to each brake system application.
REMOVAL - NON-ABS JUNCTION BLOCK
(1) Using a brake pedal depressor, move and lock
the brake pedal to a position past its first 1 inch of
travel. This will prevent brake fluid from draining
out of the master cylinder when the brake tubes are
removed from the junction block.
(2) Disconnect the battery negative cable.
(3) If the vehicle is equipped with speed control,
perform the following:
(a) Disconnect the battery positive cable.
(b) Remove the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - REMOVAL).(c) Disconnect the vacuum hose connector at the
tank built into the battery tray.
(d) Remove the screw securing the coolant filler
neck to the battery tray.
(e) Remove the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - REMOVAL).
(f) Remove the fasteners and move the speed
control servo off to the side, out of the way.
CAUTION: Before removing the brake tubes from
the junction block, the junction block and the brake
tubes must be thoroughly cleaned. This is required
to prevent contamination from entering the brake
hydraulic system.
(4) Remove the four chassis brake tubes from the
top of the junction block (Fig. 53).
(5) Remove the primary and secondary brake
tubes from the top of the junction block.
(6) Remove the bolts attaching the junction block
mounting bracket to the front suspension crossmem-
ber (Fig. 53), then remove the junction block.INSTALLATION - NON-ABS JUNCTION BLOCK
(1) Install the junction block and mounting bracket
on the front suspension crossmember (Fig. 53).
Install the mounting bolts and tighten to a torque of
28 N´m (250 in. lbs.).
(2) Install the primary and secondary brake tubes
from the master cylinder in their ports. Tighten tube
nuts to a torque of 17 N´m (145 in. lbs.).Take care
not to twist tubes when tightening tube nuts.
They must be properly positioned to allow free
movement with rubber isolated suspension
crossmember.
Fig. 53 NON-ABS JUNCTION BLOCK
1 - MASTER CYLINDER
2 - JUNCTION BLOCK
3 - SUSPENSION CROSSMEMBER
4 - MOUNTING BOLTS
5 - 36 BRAKES - BASERS
FLUID (Continued)
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(27) Install lower steering column cover/knee
blocker (Fig. 62).
(28) Install silencer panel below lower steering col-
umn cover/knee blocker.
NOTE: When reconnecting the battery on a vehicle
that has had the airbag module removed, the fol-
lowing procedure should be used.
(29) Reconnect ground cable to negative post of
battery in following manor:
(a) Connect scan tool (DRBIIIt) to data link
diagnostic connector located below steering column.
(b) Turn ignition key to ON position. Exit vehi-
cle with scan tool leaving scan tool harness
plugged in.
(c) Ensuring that there are no occupants in vehi-
cle, connect ground (-) cable to the negative post of
the battery.
(d) Using scan tool, read and record any airbag
fault codes. Refer to Appropriate Diagnostic Infor-
mation if any faults are found.
(e) Through drivers open window, Reach around
back of steering wheel (between steering wheel and
instrument cluster) and turn ignition key to OFF,
then back ON while observing instrument cluster
airbag indicator lamp. It should go on for six to
eight seconds, then go out. This action indicates
that airbag system is functioning normally. If air-
bag indicator lamp fails to light, blinks on and off,
or goes on and stays on, there is an airbag system
malfunction. Refer to Appropriate Diagnostic Infor-
mation to diagnose the system malfunction.
(30) Using scan tool (DRBIIIt), check for and clear
any existing adjustable pedal fault codes. The adjust-
able pedal system is now activated.
(31) Turn key to OFF and remove scan tool from
vehicle.
(32) Test operation of adjustable pedals, memory
seats (if equipped), RKE (if equipped), and all func-
tions that are steering column operated. If applica-
ble, reset the radio and the clock.
(33) Road test the vehicle to ensure proper opera-
tion of the steering and brake systems.
PEDAL TORQUE SHAFT - RHD
REMOVAL
(1) Remove the instrument panel. (Refer to 23 -
BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - REMOVAL)
(2) Remove the HVAC housing. (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - REMOVAL)
(3) Remove the retaining clip at the torque shaft
end of the brake pedal-to-torque shaft link. Removethe link from the torque shaft. Discard the retaining
clip. It is not to be reused. Replace with a new clip
when reassembled.
(4) Locate the booster input rod-to-brake pedal
torque shaft connection and remove the retaining clip
(Fig. 73). Discard the retaining clip. It is not to be
reused. Replace with a new clip when reassembled.
(5) Remove the four (4) brake booster retaining
nuts from inside the passenger compartment (Fig.
74).
(6) Remove the retaining nut from the brake
booster bracket located above the booster in the
engine compartment (Fig. 74).
(7) Remove the power brake booster bracket.
(8) Rotate the pedal torque shaft and remove it out
the left side of the vehicle.
INSTALLATION
(1) Lubricate both ends of the torque shaft with
MS-4517 Lubricant or equivalent and install the
torque shaft from the left side reversing the removal
procedure.
(2) Install the brake booster bracket on the left
end of the shaft.
(3) Install the four brake booster retaining nuts
inside the passenger compartment. Tighten the
mounting nuts to a torque of 29 N´m (250 in. lbs.).
(4) Install the retaining nut for the brake booster
bracket in the engine compartment. Tighten the
mounting nuts to a torque of 29 N´m (250 in. lbs.).
(5) Using lubriplate, or equivalent, coat the sur-
face of the brake pedal torque shaft pin where it con-
tacts the booster input rod. Also coat the surface of
Fig. 73 POWER BRAKE BOOSTER BRACKET
1 - BOOSTER BRACKET
2 - PEDAL TORQUE SHAFT
3 - RETAINING CLIP
4 - BOOSTER MOUNTING NUTS
RSBRAKES - BASE5-47
PEDAL - ADJUSTABLE (Continued)
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(8) With the aid of a helper, apply pressure to the
brake pedal until a pressure of 6895 kPa (1000 psi) is
obtained on the proportioning valve inlet gauge.
Then, based on the type of brake system the vehicle
is equipped with and the pressure specification
shown on the following table, compare the pressure
reading on the outlet gauge to the specification. If
outlet pressure at the proportioning valve is not
within specification when required inlet pressure is
obtained, replace the proportioning valve. (Refer to 5
- BRAKES/HYDRAULIC/MECHANICAL/PROPOR-
TIONING VALVE - REMOVAL)
CAUTION: Do not attempt to adjust the height sens-
ing proportioning valve. If found to be defective,
replace the valve.(9) Remove the pressure test fittings and pressure
gauges from the proportioning valve.
(10) Install the chassis brake lines in the correct
ports of the proportioning valve. Tighten all tube
nuts to 17 N´m (145 in. lbs.).
(11) If necessary, repeat the above steps on the
remaining side of the proportioning valve which con-
trol the other rear wheel brake.
(12) Attach the actuator lever and bracket to the
rear axle.
(13) Bleed rear brakes. (Refer to 5 - BRAKES -
STANDARD PROCEDURE)
(14) Road test vehicle.
PROPORTIONING VALVE SPECIFICATIONS
WHEEL
BASEDRIVE
TRAINSALES CODE BRAKE SYSTEMSPLIT
POINTSLOPEINLET
PRESSURE
PSIOUTLET
PRESSURE
PSI
SWB FWD BRB-BGF159DISC/DRUM
W/O ANTILOCKVAR. .59 1000 PSI 675-875 PSI
REMOVAL - PROPORTIONING VALVE (HEIGHT
SENSING)
(1) Using a brake pedal depressor, move and lock
the brake pedal to a position past its first 1 inch of
travel. This will prevent brake fluid from draining
out of the master cylinder when the brake tubes are
removed from the proportioning valve.
(2) Raise vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE).
CAUTION: Before removing the brake tubes from
the proportioning valve, the proportioning valve and
the brake tubes must be thoroughly cleaned. This is
required to prevent contamination from entering the
proportioning valve or the brake tubes.
(3) Remove the four brake tubes from the inlet and
outlet ports of the proportioning valve (Fig. 92).
(4) Remove the two bolts attaching the proportion-
ing valve and bracket to the vehicle (Fig. 92).
(5) Slide the bracket out from under rear track bar
bracket. Lower the valve down enough to pull its
actuator rod out of the axle bracket and remove the
proportioning valve from the vehicle.
Fig. 92 PROPORTIONING VALVE MOUNTING
1 - LEFT REAR OUTLET TUBE
2 - RIGHT REAR OUTLET TUBE
3 - RIGHT REAR INLET TUBE
4 - MOUNTING BOLTS
5 - LEFT REAR INLET TUBE
5 - 58 BRAKES - BASERS
PROPORTIONING VALVE (Continued)
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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

HCU (HYDRAULIC CONTROL
UNIT)
DESCRIPTION
The hydraulic control unit (HCU) is mounted to
the CAB as part of the ICU (Fig. 22). The HCU con-
trols the flow of brake fluid to the brakes using a
series of valves and accumulators. A pump/motor is
mounted on the HCU to supply build pressure to the
brakes during an ABS stop.
The HCU on a vehicle equipped with ABS and
traction control has a valve block housing that is
approximately 1 inch longer on the low pressure fluid
accumulators side than a HCU on a vehicle that is
equipped with only ABS.
For more information, (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/ICU (INTEGRATED CON-
TROL UNIT) - DESCRIPTION)
OPERATION
For information on the operation of the HCU as a
whole, refer to Hydraulic Circuits And Valve Opera-
tion which can be found elsewhere in this section.
For information on the operation of the components
within the HCU, refer to the following three topics.
VALVES AND SOLENOIDS
The valve block contains four inlet valves and four
outlet valves. The inlet valves are spring-loaded in
the open position and the outlet valves are spring-
loaded in the closed position during normal braking.
The fluid is allowed to flow from the master cylinder
to the wheel brakes.
During an ABS stop, these valves cycle to maintain
the proper slip ratio for each wheel. The inlet valve
closes preventing further pressure increase and the
outlet valve opens to provide a path from the wheel
brake to the HCU accumulators and pump/motor.
This releases (decays) pressure from the wheel brake,
thus releasing the wheel from excessive slippage.
Once the wheel is no longer slipping, the outlet valve
is closed and the inlet valve is opened to reapply
(build) pressure.
On vehicles with traction control, there is an extra
set of valves and solenoids. The ASR valves, mounted
in the HCU valve block, are normally in the open
position and close only when the traction control is
applied.
These isolator valves are used to isolate the rear
(non-driving) wheels of the vehicle from the hydraulicpressure that the HCU pump/motor is sending to the
front (driving) wheels when traction control is being
applied. The rear brakes need to be isolated from the
master cylinder when traction control is being
applied so the rear wheels do not drag. For more
information, refer to Traction Control System in this
section.
BRAKE FLUID ACCUMULATORS
There are two fluid accumulators in the HCU±one
for the primary hydraulic circuit and one for the sec-
ondary hydraulic circuit. Each hydraulic circuit uses
a 5 cc accumulator.
The fluid accumulators temporarily store brake
fluid that is removed from the wheel brakes during
an ABS cycle. This stored fluid is used by the pump/
motor to provide build pressure for the brake hydrau-
lic system. When the antilock stop is complete, the
accumulators are drained by the pump/motor.
On ABS-only vehicles, there is a mini-accumulator
on the secondary hydraulic circuit that protects the
master cylinder seals during an ABS stop, and there
is a noise dampening chamber on the primary circuit.
On ABS with traction control vehicles, there are
two noise dampening chambers in the HCU.
PUMP/MOTOR
There are two pump assemblies in the HCUÐone
for the primary hydraulic circuit and one for the sec-
ondary hydraulic circuit. Both pumps are driven by a
common electric motor. This DC-type motor is inte-
gral to the HCU and is controlled by the CAB.
The pump/motor provides the extra amount of
brake fluid needed during antilock braking. Brake
fluid is released to the accumulators when the outlet
valve is opened during an antilock stop. The pump
mechanism consists of two opposing pistons operated
by an eccentric camshaft. In operation, one piston
draws fluid from the accumulators, and the opposing
piston pumps fluid to the master cylinder circuits.
When the antilock stop is complete, the pump/motor
drains the accumulators.
The CAB may turn on the pump/motor when an
antilock stop is detected. The pump/motor continues
to run during the antilock stop and is turned off after
the stop is complete. Under some conditions, the
pump/motor runs to drain the accumulators during
the next drive-off.
The pump/motor is not a serviceable item; if it
requires replacement, the HCU must be replaced.
RSBRAKES - ABS5-99
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(2) Remove the driver airbag from the steering
wheel (Refer to 8 - ELECTRICAL/RESTRAINTS/
DRIVER AIRBAG - REMOVAL).
(3) Remove the plastic wire retainer that captures
the horn switch feed pigtail wire between the upper
left inflator stud and the inflator on the back of the
driver airbag housing.
(4) Remove the four nuts that secure the upper
and lower trim cover retainers to the studs on the
back of the driver airbag housing.
(5) Remove the upper and lower trim cover retain-
ers from the airbag housing studs.
(6) Remove the horn switch ground pigtail wire
eyelet terminal from the upper right airbag housing
stud.
(7) Disengage the six trim cover locking blocks
from the lip around the outside edge of the driver
airbag housing and remove the housing from the
cover.
INSTALLATION
(1) Install the housing into the cover. Engage the
six trim cover locking blocks to the lip around the
outside edge of the driver airbag housing.
(2) Install the horn switch ground pigtail wire eye-
let terminal to the upper right airbag housing stud.
(3) Install the upper and lower trim cover retain-
ers to the airbag housing studs.
(4) Install the four nuts that secure the upper and
lower trim cover retainers to the studs on the back of
the driver airbag housing.
(5) Install the plastic wire retainer that captures
the horn switch feed pigtail wire between the upper
left inflator stud and the inflator on the back of the
driver airbag housing.
(6) Install the driver airbag onto the steering
wheel (Refer to 8 - ELECTRICAL/RESTRAINTS/
DRIVER AIRBAG - INSTALLATION).
WARNING: DO NOT CONNECT THE BATTERY NEG-
ATIVE CABLE. FIRST (Refer to 8 - ELECTRICAL/RE-
STRAINTS/DIAGNOSIS AND TESTING - AIRBAG
SYSTEM).
OCCUPANT RESTRAINT
CONTROLLER
DESCRIPTION
The front driver and passenger airbag system is
designed to reduce the risk of fatality or serious
injury, caused by a frontal impact of the vehicle.
The Occupant Restraint Controller (ORC) contains
the impact sensor and energy reserve capacitor. It is
mounted on a bracket, under the instrument panel,just forward of the storage bin. The ORC monitors
the system to determine the system readiness. The
ORC contains on-board diagnostics and will light the
AIRBAG warning lamp in the message center when a
problem occurs.
OPERATION
The impact sensor provides verification of the
direction and severity of the impact. One impact sen-
sor is used. It is located inside the Occupant
Restraint Controller (ORC). The impact sensor is an
accelerometer that senses deceleration. The decelera-
tion pulses are sent to a microprocessor which con-
tains a decision algorithm. When an impact is severe
enough to require airbag protection, the ORC micro-
processor sends a signal that completes the electrical
circuit to the driver and passenger airbags. The
impact sensor is calibrated for the specific vehicle
and reacts to the severity and direction of an impact.
REMOVAL
NOTE: Diagnose the ORC using the service/diag-
nostic manual.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove storage bin from instrument panel.
Refer to Body, Instrument Panel, Storage Bin,
Removal.
(3) Remove three bolts holding ORC to floor
bracket.
(4) Disconnect the wire connector from ORC.
(5) Remove the ORC assembly from vehicle.
INSTALLATION
WARNING: DO NOT INSTALL ORC IF MOUNTING
LOCATION IS DEFORMED OR DAMAGED.
CAUTION: Use correct screws when installing the
ORC.
(1) Install the ORC assembly into vehicle.
(2) Connect the wire connector to the ORC.
(3) Install three bolts holding ORC to floor
bracket. Torque bolts to 7.3 - 9.6 N´m (65 to 85 in.
lbs.)
(4) Install the storage bin onto the instrument
panel. Refer to Body, Instrument Panel, Storage Bin,
Installation.
WARNING: DO NOT CONNECT THE BATTERY NEG-
ATIVE CABLE. REFER TO ELECTRICAL,
RESTRAINTS, DIAGNOSIS AND TESTING - AIRBAG
SYSTEM FIRST.
RSRESTRAINTS8O-5
DRIVER AIRBAG TRIM COVER (Continued)
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(6) Install the accessory drive belt. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION)
(7) Install inner splash shield and right front
wheel.
(8) Connect negative cable to battery.
ENGINE MOUNTING
DESCRIPTION
The engine mounting system consist of four
mounts; right and a left side support the powertrain,
and a front and a rear mount control powertrain
torque. The right side mount is a hydro-type (Fig.
91), all others are of molded rubber material.
FRONT MOUNT
REMOVAL
(1) Support the engine and transmission assembly
with a floor jack so it will not rotate.
(2) Remove the front engine mount through bolt
from the insulator and front crossmember mounting
bracket (Fig. 92).
(3) Remove six screws from air dam to allow
access to the front mount screws.
(4) Remove the front engine mount screws and
remove the insulator assembly (Fig. 92).
(5) Remove the front mounting bracket, if neces-
sary (Fig. 92).
INSTALLATION
(1) Install the front mounting bracket, if removed
(Fig. 92).
(2) Install the front engine mount through bolt
from the insulator and front crossmember mounting
bracket (Fig. 92).
(3) Install the insulator assembly and mounting
screws (Fig. 92).
Fig. 90 Vibration Damper - Installation
1 - FORCING SCREW / NUT FROM SPECIAL TOOL 8452
2 - VIBRATION DAMPER
3 - THRUST BEARING / WASHER
Fig. 91 Engine Hydro-type Mount - Right Side
1 - BOLT
2 - BOLT
3 - FRAME RAIL
4 - RIGHT MOUNT - 2.4L ENGINE
5 - RIGHT MOUNT - 3.3/3.8L ENGINE
RSENGINE 3.3/3.8L9 - 133
VIBRATION DAMPER (Continued)
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