2003 CHRYSLER CARAVAN wheel

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 hydraulic
pressure 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 moreinformation, 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.
ICU (INTEGRATED CONTROL
UNIT)
DESCRIPTION
The hydraulic control unit (HCU) and the control-
ler antilock brake (CAB) used with this antilock
brake system are combined (integrated) into one
unit, which is called the integrated control unit (ICU)
RSBRAKES - ABS5-89
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(10) Disconnect the 24±way connector from the
CAB. To disconnect the 24±way connector, grasp the
lock on the 24±way connector and pull it as far up as
possible. This will unlock the 24±way connector from
the socket on the CAB.
CAUTION: Before removing the brake tubes from
the HCU, the HCU must be thoroughly cleaned. This
must be done to prevent dirt particles from falling
into the ports of HCU or entering the brake tubes.
(11) Thoroughly clean all surfaces of the ICU and
brake tube nuts. Use only a solvent such as Mopart
Brake Parts Cleaner or equivalent to clean the ICU.
(12) Remove the brake tubes (4) from the outlet
ports on the HCU (Fig. 14).
(13) Remove the primary and secondary brake
tubes from the inlet ports on the HCU (Fig. 14).
(14) Center and prop the steering wheel.
(15) Remove the pinch bolt and disconnect the
steering shaft coupling.
(16) If equipped, remove the two clips securing
silencer to dash seal (Fig. 15). Remove silencer.
(17) Remove the three screws securing the dash
seal (Fig. 15). Remove seal.
(18) Remove the 3 bolts attaching the ICU to its
mounting bracket (Fig. 16).
(19) Remove ICU from the vehicle through engine
compartment.
(20) If required, to separating the CAB from the
HCU, (Refer to 5 - BRAKES - ABS/HYDRAULIC/ME-
CHANICAL/ICU (INTEGRATED CONTROL UNIT) -
DISASSEMBLY).
REMOVAL - RHD
NOTE: Before proceeding, (Refer to 5 - BRAKES -
WARNING)(Refer to 5 - BRAKES - CAUTION)
(1) Disconnect the negative (ground) cable from
the battery and isolate cable.
Fig. 14 Brake Tube Nuts At ICU
1 - PRIMARY BRAKE TUBE
2 - SECONDARY BRAKE TUBE
3 - CHASSIS BRAKE TUBES
Fig. 15 Lower Coupling And Dash Seal
1 - COUPLING
2 - DASH SEAL
3 - SILENCER
4 - MOUNTING SCREWS
5 - RETAINING CLIPS
6 - DASH
Fig. 16 ICU Mounting Bolts
1 - ICU MOUNTING BOLTS
2 - COUPLER
RSBRAKES - ABS5-91
ICU (INTEGRATED CONTROL UNIT) (Continued)
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(2) Using a brake pedal depressor, move and lock
the brake pedal to a position past the first inch of
pedal travel.This will prevent brake fluid from
draining out of the master cylinder when the
brake tubes are removed from the HCU.
(3) Raise vehicle. (Refer to LUBRICATION &
MAINTENANCE/HOISTING - STANDARD PROCE-
DURE)
(4) Remove the routing clip attaching the ICU wir-
ing harness to the ICU mounting bracket (Fig. 17).
CAUTION: Do not apply a 12 volt power source to
any terminals of the HCU connector when discon-
nected.
(5) Remove the 24-way connector (Fig. 17) from
the CAB. The 24-way connector is removed from the
CAB using the following procedure. Grasp the lock
on the 24-way connector (Fig. 17) and pull it as far
out as possible (Fig. 18). This will raise and unlock
the 24-way connector from the socket on the CAB.
CAUTION: Before removing the brake tubes from
the HCU, the HCU must be thoroughly cleaned. This
must be done to prevent dirt particles from falling
into the ports of HCU or entering the brake tubes.(6) Thoroughly clean all surfaces of the HCU, and
all brake tube nuts located on the HCU. Use only a
solvent such as Mopar Brake Parts Cleaner or an
equivalent to clean the HCU.
(7) Remove the brake tubes (6) from the inlet and
outlet ports on the HCU. (Fig. 19).
Fig. 17 CAB 24-Way Connector
1 - CAB WIRING HARNESS
2 - 24±WAY CONNECTOR
3 - FLOOR PAN
4 - HCU
5 - CAB
6 - HCU MOUNTING BRACKET
7 - CONNECTOR LOCK
Fig. 18 Unlocked 24-Way CAB Connector
1 - HCU
2 - CAB
3 - 24±WAY CONNECTOR
4 - CONNECTOR LOCK (UNLOCKED)
Fig. 19 Brake Tube Connections To HCU
1 - LEFT REAR WHEEL BRAKE TUBE
2 - SECONDARY BRAKE TUBE FROM MASTER CYLINDER
3 - LEFT FRONT WHEEL BRAKE TUBE
4 - CAB
5 - RIGHT REAR WHEEL BRAKE TUBE
6 - HCU MOUNTING BRACKET
7 - BRAKE TUBE TO HCU CONNECTION LOCATION LEGEND
8 - RIGHT FRONT WHEEL BRAKE TUBE
9 - PRIMARY BRAKE TUBE FROM MASTER CYLINDER
5 - 92 BRAKES - ABSRS
ICU (INTEGRATED CONTROL UNIT) (Continued)
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ASSEMBLY - ICU
(1) Install the CAB (Fig. 24) on the HCU.
(2) Install the 4 bolts mounting the CAB (Fig. 23)
to the HCU. Tighten the CAB mounting bolts to a
torque of 2 N´m (17 in. lbs.).
(3) Plug the pump/motor wiring harness into the
CAB.
(4) Install the ICU in the vehicle and bleed the
base and ABS hydraulic systems. (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/ICU (INTE-
GRATED CONTROL UNIT) - INSTALLATION)
INSTALLATION
INSTALLATION - LHD
(1) Place the ICU in its bracket below the master
cylinder. Start the upper mounting bolt to hold it in
place.
(2) Inside the vehicle, install the remaining 2
mounting bolts attaching the ICU to the mounting
bracket (Fig. 16). Tighten all 3 mounting bolts to a
torque of 11 N´m (97 in. lbs.).
(3) Install the dash seal and three mounting
screws (Fig. 15).
(4) If equipped, install the silencer on top of the
dash seal (Fig. 15).
(5) Connect the steering shaft coupling and install
the pinch bolt (Fig. 15). Tighten the pinch bolt to 28
N´m (250 in. lbs.).
(6) Remove the steering wheel holder.
CAUTION: Because of the flexible section in the pri-
mary and secondary brake tubes, the brake tubes
must be held in proper orientation when tightened
and torqued. These tubes must not contact eachother or other vehicle components when installed.
Also, after the brake tubes are installed on the HCU,
ensure all spacer clips are reinstalled on the brake
tubes.
(7) Install the primary and secondary brake tubes
into their correct port locations on the HCU valve
block (Fig. 14). Tighten the tube nuts to a torque of
17 N´m (145 in. lbs.).
CAUTION: When installing the chassis brake tubes
on the HCU valve block, they must be located cor-
rectly in the valve block to ensure proper ABS oper-
ation.
NOTE: The chassis brake tube attachment locations
to the HCU, are marked on the bottom of the CAB.
(8) Install the (4) chassis brake tubes into their
correct port locations on the HCU valve block as
shown (Fig. 14). Tighten the tube nuts to a torque of
17 N´m (145 in. lbs.).
NOTE: Before installing the 24±way connector in
the CAB be sure the seal is properly installed in the
connector.
(9) Install the 24±way connector on the CAB by,
first, positioning the 24±way connector in the socket
of the CAB and carefully pushing it down as far as
possible. Once connector is fully seated by hand into
the CAB socket, push down on connector lock. This
will pull the connector into the socket of the CAB
and lock it in the installed position.
(10) Install any routing clips on the brake tubes.
(11) Remove the brake pedal holder.
(12) Install the speed control servo with its mount-
ing nuts.
(13) Connect the wiring harness to the speed con-
trol servo.
(14) Install the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - INSTALLA-
TION).
(15) Install the screw securing the coolant filler
neck to the battery tray.
(16) Reconnect the vacuum hose connector at the
tank built into the battery tray.
(17) Install the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - INSTALLA-
TION).
(18) Install the battery shield.
(19) Remove the brake pedal holder.
(20) Connect negative cable back on negative post
of the battery.
(21) Bleed the Base and ABS brake hydraulic sys-
tems (Refer to 5 - BRAKES - STANDARD PROCE-
DURE).
Fig. 24 (TYPICAL) Remove/Install CAB
1 - CAB
2 - HCU VALVES
3 - HCU VALVE BLOCK
5 - 94 BRAKES - ABSRS
ICU (INTEGRATED CONTROL UNIT) (Continued)
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CLUTCH
TABLE OF CONTENTS
page page
CLUTCH
DESCRIPTION..........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - CLUTCH
SYSTEM.............................3
DIAGNOSIS AND TESTING - DRIVE PLATE
MISALIGNMENT.......................6
DIAGNOSIS AND TESTING - CLUTCH
COVER AND DISC RUNOUT..............6
DIAGNOSIS AND TESTING - CLUTCH
CHATTER COMPLAINTS.................6
SPECIAL TOOLS - T850 TRANSAXLE........6
CLUTCH RELEASE LEVER AND BEARING
REMOVAL.............................6
INSTALLATION..........................7
MASTER CYLINDER - RHD
REMOVAL.............................8
INSTALLATION..........................9
MASTER CYLINDER - LHD
REMOVAL.............................9INSTALLATION.........................10
MODULAR CLUTCH ASSY - 2.4L GAS
REMOVAL.............................11
INSTALLATION.........................11
SLAVE CYLINDER
REMOVAL.............................11
INSTALLATION.........................11
CLUTCH DISC AND PRESSURE PLATE - 2.5L TD
REMOVAL.............................11
INSTALLATION.........................12
FLYWHEEL
REMOVAL.............................12
INSTALLATION.........................12
CLUTCH PEDAL INTERLOCK SWITCH
REMOVAL.............................13
INSTALLATION.........................14
CLUTCH PEDAL UPSTOP SWITCH
REMOVAL.............................15
INSTALLATION.........................16
CLUTCH
DESCRIPTION
CLUTCH COMPONENTS
Models equipped with a 2.4L Gas engine utilize a
modular clutch assembly (Fig. 1). The modular clutch
consists of a single, dry-type clutch disc, a diaphragm
style clutch cover, and an integrated flywheel. The
clutch cover (pressure plate) is riveted to the fly-
wheel, and therefore can only be serviced as an
assembly.
Models equipped with the 2.5L Turbo Diesel engine
utilize a conventional clutch system (Fig. 2). This
system consists of a flywheel, clutch disc, and clutch
cover (pressure plate), which is fastened to the fly-
wheel, capturing the clutch disc within. Each compo-
nent is individually serviceable, however it ishighly
recommended that the clutch cover and disc be
replaced as a set.
Fig. 1 Modular Clutch AssemblyÐ2.4L Gas Engines
1 - MODULAR CLUTCH ASSEMBLY
RSCLUTCH6-1
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Fig. 2 Clutch Disc and Pressure PlateÐ2.5L TD Engines
1 - FLYWHEEL
2 - DISC
3 - PRESSURE PLATE
6 - 2 CLUTCHRS
CLUTCH (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
CLUTCH DISC FACINGS
HAVE FRACTURED
INTO SMALL PIECESLeak at rear main or transaxle input
shaft sealReplace seal. Replace modular clutch
assembly (2.4L Gas) or clutch cover and disc
(2.5L TD)..
Excessive heat from slippage Replace modular clutch assembly (2.4L Gas)
or clutch cover and disc (2.5L TD).
SERVICE DIAGNOSIS - IMPROPER CLUTCH RELEASE
CONDITION POSSIBLE CAUSES CORRECTION
CLUTCH DISC BINDS
ON INPUT SHAFT
SPLINESClutch disc hub splines damaged
during installationClean, smooth, and lubricate disc and shaft
splines. Replace modular clutch assembly, or
clutch disc, and/or input shaft if splines are
severely damaged.
Input shaft splines rough, damaged. Clean input shaft splines. Then lube.
Corrosion or rust formations on
splines of input shaft and discClean input shaft splines and disc splines,
then lube
CLUTCH DISC RUSTED
TO FLYWHEEL AND/OR
PRESSURE PLATEOccurs in vehicles stored or not
driven for extended period of time.
Also occurs after steam cleaning if
vehicle is not used for extended
period.Replace modular clutch assembly (2.4L Gas)
or clutch cover and disc (2.5L TD).
CLUTCH WILL NOT
DISENGAGE PROPERLYDisc bent, distorted during transaxle
installationReplace modular clutch assembly (2.4L Gas)
or clutch cover and disc (2.5L TD).
Clutch cover diaphragm spring
damaged during transaxle installationReplace modular clutch assembly (2.4L Gas)
or clutch cover and disc (2.5L TD).
Release fork bent, loose, or
damagedReplace fork if worn or damaged
Air in clutch hydraulic circuit. Allow system to self-bleed or replace
hydraulic components.
Leak in clutch hydraulic circuit. Replace worn/damaged/leaking hydraulic
components.
Clutch pedal requires
excessive force (high
release load).Clutch disc is worn. Replace modular clutch assembly (2.4L
models) or clutch cover and disc (2.5L TD
models).
SERVICE DIAGNOSIS - CLUTCH PEDAL NOISE
CONDITION POSSIBLE CAUSES CORRECTION
CLUTCH PEDAL
SQUEAKS WHEN
DEPRESSED TO FLOORPedal bushings worn out or
inadequate lubricationReplace or lubricate bushings at clutch pedal
pivot or master cylinder pushrod.
Clutch pedal return spring worn out Lubricate or replace return spring
CLUTCH PEDAL
SQUEAKS DURING
OPERATIONClutch release lever pivot stud has
inadequate lubricationLubricate or replace clutch release lever
RSCLUTCH6-5
CLUTCH (Continued)
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DIAGNOSIS AND TESTING - DRIVE PLATE
MISALIGNMENT
Common causes of misalignment are:
²Heat warping
²Mounting drive plate on a dirty crankshaft
flange
²Incorrect bolt tightening
²Improper seating on the crankshaft shoulder
²Loose crankshaft bolts
Clean the crankshaft flange before mounting the
drive plate. Dirt and grease on the flange surface
may misalign the flywheel, causing excessive runout.
Use new bolts when mounting drive plate to crank-
shaft. Tighten drive plate bolts to specified torque
only. Over-tightening can distort the drive plate hub
causing excessive runout.
DIAGNOSIS AND TESTING - CLUTCH COVER
AND DISC RUNOUT
Check condition of the clutch cover before installa-
tion. A warped cover or diaphragm spring will cause
grab and/or incomplete release or engagement. Use
care when handling the clutch assembly. Impact can
distort the cover, diaphragm spring, and release fin-
gers.
DIAGNOSIS AND TESTING - CLUTCH CHATTER
COMPLAINTS
For all clutch chatter complaints, perform the fol-
lowing:
(1) Check for loose, misaligned, or broken engine
and transmission mounts. If present, they should be
corrected at this time. Test vehicle for chatter. If
chatter is gone, there is no need to go any further.
(2) If chatter persists, check hydraulic clutch
release system is functioning properly.
(3) Check for loose connections in drivetrain. Cor-
rect any problems and determine if clutch chatter
complaints have been satisfied. If not:
(a) Remove transaxle.
(b) Check to see if the release bearing is sticky
or binding. Replace bearing, if needed.
(c) Check linkage for excessive wear on the pivot
stud and fork fingers. Replace all worn parts.
(d) Check clutch assembly for contamination
(dirt, oil). Replace clutch assembly, if required.
(e) Check to see if the clutch disc hub splines
are damaged. Replace with new clutch assembly, if
necessary.
(f) Check input shaft splines for damage.
Replace, if necessary.
(g) Check for uneven wear on clutch fingers.
(h) Check for broken clutch cover diaphragm
spring fingers. Replace with new clutch assembly,
if necessary.
SPECIAL TOOLS - T850 TRANSAXLE
CLUTCH RELEASE LEVER AND
BEARING
REMOVAL
(1) Remove transaxle assembly. (Refer to 21 -
TRANSMISSION/TRANSAXLE/MANUAL -
REMOVAL)
(2) Remove modular clutch assembly from input
shaft (2.4L Gas models only).
(3) Grasp clutch release lever and bearing (Fig. 6)
with both hands and pull outward using moderate
pressure to release lever from pivot ball.
(4) Separate release bearing from lever.
NOTE: Remove release lever pivot ball(s) ONLY if
replacement is necessary.
Disconnect Tool, 6638A
Remover/Installer, 6891
6 - 6 CLUTCHRS
CLUTCH (Continued)
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