Air flow JEEP GRAND CHEROKEE 2002 WJ / 2.G Owner's Manual

INSPECTION
The radiator cooling fins should be checked for
damage or deterioration. Inspect cooling fins to make
sure they are not bent or crushed, these areas result
in reduced heat exchange causing the cooling system
to operate at higher temperatures. Inspect the plastic
end tanks for cracks, damage or leaks.
Inspect the radiator neck for damage or distortion.
INSTALLATION
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals (Fig. 39) are
properly fastened to their original positions. These
are used at the top, bottom and sides of the radia-
tor and A/C condenser. To prevent overheating,
these seals must be installed to their original posi-
tions.
(1) Equipped with air conditioning: Gently lower
the radiator into the vehicle. Guide the two radiator
alignment dowels through the holes in the rubber air
seals first and then through the A/C support brackets
(Fig. 40). Continue to guide the alignment dowels
into the rubber grommets located in lower radiator
crossmember. The holes in the L-shaped brackets
(located on bottom of A/C condenser) must be posi-
tioned between bottom of rubber air seals and top of
rubber grommets.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator (Fig. 41).
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator (Fig. 41).
(4) Connect both transmission cooler lines at the
radiator (Fig. 41).
(5) Install both radiator mounting bolts (Fig. 41).
(6) Install air inlet duct at grill.
(7) Attach electric fan harness to shroud, then con-
nect harness to connector (Fig. 41).
(8) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(9) Install the fan/viscous fan drive assembly to
the water pump.
(10) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(11) Be sure of at least 25 mm (1.0 inch) between
tips of fan blades and fan shroud.
(12) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(13) Connect battery cable at battery.
(14) Start and warm engine. Check for leaks.
RADIATOR FAN MOTOR
DIAGNOSIS AND TESTINGÐELECTRIC
COOLING FAN
The powertrain control module (PCM) will enter a
diagnostic trouble code (DTC) in memory if it detects
a problem in the auxiliary cooling fan relay or circuit.
(Refer to 25 - EMISSIONS CONTROL - DESCRIP-
TION).
If the electric cooling fan is inoperative, check the
15A fuse in the junction block and the 40A fuse in
the Power Distribution Center (PDC) with a 12 volt
test lamp or DVOM. Refer to the inside of the PDC
cover for the exact location of the fuse. If fuses are
okay, refer to ELECTRICAL for cooling fan and relay
circuit schematic.
WATER PUMP - 4.7L
DESCRIPTION
DESCRIPTIONÐWATER PUMP
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
single serpentine drive belt.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary.
Both heater hoses are connected to fittings on the
timing chain front cover. The water pump is also
mounted directly to the timing chain cover and is
equipped with a non serviceable integral pulley (Fig.
42).
DESCRIPTIONÐWATER PUMP BYPASS
The 4.7L engine uses an internal water/coolant
bypass system. The design uses galleries in the tim-
ing chain cover to circulate coolant during engine
warm-up preventing the coolant from flowing
through the radiator. The thermostat uses a stub
shaft located at the rear of the thermostat (Fig. 43)
to control flow through the bypass gallery.
OPERATION
OPERATIONÐWATER PUMP
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
WJENGINE 7 - 47
RADIATOR - 4.0L (Continued)

CAUTION: When installing the serpentine engine
accessory drive belt, the belt MUST be routed cor-
rectly. If not, the engine may overheat due to the
water pump rotating in the wrong direction. Refer to
the Belt Removal and Installtion in this group for
appropriate belt routing. You may also refer to the
Belt Routing Label in the vehicle engine compart-
ment.
Install accessory drive belt (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
(6) Install fan blade and viscous fan drive onto
water pump.
(7) Fill cooling system with coolant and check for
leaks. (Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(8) Connect battery cable to battery.
(9) Start and warm the engine. Check for leaks.
RADIATOR PRESSURE CAP
DESCRIPTION
All radiators are equipped with a pressure cap
(Fig. 50). This cap releases pressure at some point
within a range of 124-to-145 kPa (18-to-21 psi). The
pressure relief point (in pounds) is engraved on top of
the cap
The cooling system will operate at pressures
slightly above atmospheric pressure. This results in a
higher coolant boiling point allowing increased radi-
ator cooling capacity. The cap contains a spring-
loaded pressure relief valve. This valve opens when
system pressure reaches the release range of 124-to-
145 kPa (18-to-21 psi).
A rubber gasket seals the radiator filler neck. This is
done to maintain vacuum during coolant cool-down and
to prevent leakage when system is under pressure.
OPERATION
A vent valve in the center of the cap will remain
shut as long as the cooling system is pressurized. As
the coolant cools, it contracts and creates a vacuum
in cooling system. This causes the vacuum valve to
open and coolant in reserve/overflow tank to be
drawn through connecting hose into radiator. If the
vacuum valve is stuck shut, or overflow hose is
kinked, radiator hoses will collapse on cool-down.
DIAGNOSIS AND TESTINGÐRADIATOR
PRESSURE CAP
Remove cap from radiator. Be sure that sealing
surfaces are clean. Moisten rubber gasket with water
and install the cap on pressure tester (tool 7700 or
an equivalent) (Fig. 51).Operate the tester pump and observe the gauge
pointer at its highest point. The cap release pressure
should be 124 to 145 kPa (18 to 21 psi). The cap is
satisfactory when the pressure holds steady. It is also
good if it holds pressure within the 124 to 145 kPa
(18 to 21 psi) range for 30 seconds or more. If the
pointer drops quickly, replace the cap.
CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks, which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.CLEANING
Clean the radiator pressure cap using a mild soap
and water only.
Fig. 50 Radiator Pressure Cap - Typical
1 - FILLER NECK SEAL
2 - VACUUM VENT VALVE
3 - PRESSURE RATING
4 - PRESSURE VALVE
WJENGINE 7 - 53
WATER PUMP - 4.0L (Continued)

(2) If equipped, remove Transmission Control Mod-
ule (TCM).
(3) Remove coolant reserve/overflow tank.
(4) Remove cover over electrical connectors. Cover
snaps onto PCM.
(5) Carefully unplug three 32±way connectors at
PCM.
(6) Remove three PCM bracket-to-body mounting
nuts (Fig. 13).
(7) Remove PCM/PCM bracket assembly from
vehicle.
(8) Remove 3 PCM-to-PCM bracket bolts (screws)
(Fig. 14).
INSTALLATION
USE THE DRBIIItSCAN TOOL TO REPRO-
GRAM THE NEW POWERTRAIN CONTROL
MODULE (PCM) WITH THE VEHICLES ORIGI-
NAL IDENTIFICATION NUMBER (VIN) AND
THE VEHICLES ORIGINAL MILEAGE. IF THIS
STEP IS NOT DONE, A DIAGNOSTIC TROUBLE
CODE (DTC) MAY BE SET.
The PCM is located on the cowl panel in right/rear
side of engine compartment (Fig. 12).
(1) Check pins in three 32±way electrical connec-
tors for damage. Repair as necessary.
(2) Install PCM to its mounting bracket. Tighten
three mounting bolts to 3 N´m (25 in. lbs.) torque.
(3) Install PCM/PCM bracket to body. Install 3
nuts and tighten 9 N´m (80 in. lbs.) torque.
(4) Install three 32±way connectors.(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install coolant reserve/overflow tank.
(7) If equipped, install Transmission Control Mod-
ule (TCM).
(8) Connect negative cable to battery.
(9) Use the DRBIIItscan tool to reprogram new
PCM with vehicles original Identification Number
(VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) is the
primary component of the Sentry Key Immobilizer
System (SKIS) (Fig. 15). The SKIM is located in the
steering column, below the ignition lock cylinder
housing. The SKIM has an integral halo-like antenna
ring that extends from one side.
The SKIM cannot be adjusted or repaired. If faulty
or damaged, the entire SKIM unit must be replaced.
OPERATION
The Sentry Key Immobilizer Module (SKIM) con-
tains a Radio Frequency (RF) transceiver and a
microprocessor. The SKIM transmits RF signals to,
and receives RF signals from the Sentry Key tran-
Fig. 14 Powertrain Control Module (PCM) Mounting
Bracket
1 - PCM BRACKET
2 - PCM
3 - PCM-TO-BRACKET SCREWS (3)
Fig. 15 Sentry Key Immobilizer Module
1 - STEERING COLUMN
2 - SKIM
3 - MOUNTING SCREW
WJELECTRONIC CONTROL MODULES 8E - 17
POWERTRAIN CONTROL MODULE (Continued)

(1) Confirm that the ignition switch is in the On
position.
(2) Ensure that the rear glass heating grid feed
and ground terminals are connected to the glass.
Confirm that the ground wire has continuity to
ground.
(3) Check the fused B(+) fuse in the Power Distri-
bution Center (PDC). The fuse must be tight in its
receptacles and all electrical connections must be
secure.
When the above steps have been completed and the
rear glass heating grid is still inoperative, one or
more of the following is faulty:
²Rear window defogger switch
²Rear window defogger relay
²Body Control Module (BCM)
²Rear window grid lines (all grid lines would
have to be broken or one of the feed wires discon-
nected for the entire system to be inoperative).
When the above steps have been completed and the
heated mirror glass heating grid is still inoperative,
one or more of the following is faulty:
²Body Control Module (BCM)
²Programmable Communications Interface (PCI)
data bus
²Driver Door Module (DDM) or Passenger Door
Module (PDM)
²Outside rear view mirror heating grids.
If turning the rear window defogger system on pro-
duces a severe voltmeter deflection, check for a short
circuit between the rear window defogger relay out-
put and the rear glass heating grid.
REAR WINDOW DEFOGGER
GRID
DESCRIPTION
The electrically heated rear window glass is stan-
dard equipment on this model. The liftgate flip-up
glass has two electrically conductive vertical bus bars
and a series of horizontal grid lines made of a silver-
ceramic material, which is baked on and bonded to
the inside surface of the glass. These grid lines and
the bus bars comprise a parallel electrical circuit. A
spade type terminal near the top of each bus bar
accept the connectors from the two coiled liftgate
wire harness take outs.
The grid lines and bus bars are highly resistant to
abrasion. However, it is possible for an open circuit
to occur in an individual grid line, resulting in no
current flow through the line. The grid lines can be
damaged or scraped off with sharp instruments. Care
should be taken when cleaning the glass or removing
foreign materials, decals, or stickers from the glass.Normal glass cleaning solvents or hot water used
with rags or toweling is recommended.
A repair kit is available to repair the grid lines and
bus bars, or to reinstall the heated glass terminals.
(Refer to 8 - ELECTRICAL/HEATED GLASS/REAR
WINDOW DEFOGGER GRID - STANDARD PROCE-
DURE)
OPERATION
The rear glass heating grid is energized and de-en-
ergized by the rear window defogger relay. The Body
Control Module (BCM) monitors the rear window
defogger switch. When the BCM receives an input
from the switch, it energizes or de-energizes the rear
window defogger relay through a hard wired control
output. The rear defogger relay switches fused bat-
tery current to the rear window grid lines through
the bus bars. The grid lines heat the rear window
glass to clear the surface of ice, snow or fog. Protec-
tion for the rear glass heating grid circuit is provided
by a fuse in the Power Distribution Center (PDC).
DIAGNOSIS AND TESTING - REAR WINDOW
DEFOGGER GRID
For complete circuit diagrams, (Refer to Appropri-
ate Wiring Information). To detect breaks in the rear
glass heating grid lines, the following procedure is
required:
(1) Turn the ignition switch to the On position.
Turn the rear window defogger system on. The rear
window defogger switch LED indicator should light.
If OK, go to Step 2. If not OK, (Refer to 8 - ELEC-
TRICAL/HEATED GLASS/REAR WINDOW DEFOG-
GER RELAY - DIAGNOSIS AND TESTING).
(2) Using a 12-volt DC voltmeter, contact the rear
glass heating grid vertical bus bar on the right side
of the vehicle with the negative lead. With the posi-
tive lead, contact the rear glass heating grid vertical
bus bar on the left side of the vehicle. The voltmeter
should read battery voltage. If OK, go to Step 3. If
not OK, repair the open rear window defogger relay
output circuit to the rear window defogger relay as
required.
(3) With the positive voltmeter lead still contacting
the rear glass heating grid vertical bus bar on the
left side of the vehicle, move the negative lead of the
voltmeter to a good body ground point. The voltage
reading should not change. If OK, go to Step 4. If not
OK, repair the ground circuit to ground as required.
(4) Connect the negative lead of the voltmeter to
the right side bus bar and touch each grid line at
midpoint C with the positive lead (Fig. 2). A reading
of approximately six volts indicates a line is good. A
reading of zero volts indicates a break in the grid
line between midpoint C and the left side rear glass
heating grid bus bar. A reading of ten to fourteen
WJHEATED GLASS 8G - 3
HEATED GLASS (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
HORN SOUNDS
CONTINUOUSLY1. Faulty horn relay. 1. Refer to Horn Relay for the proper horn relay
diagnosis and testing procedures. Replace the
horn relay or repair the shorted horn relay control
circuit, if required.
2. Faulty horn switch. 2. Refer to Horn Switch for the proper horn switch
diagnosis and testing procedures. Replace the
horn switch or repair the shorted horn switch
circuit, if required.
HORN
DESCRIPTION
The dual electromagnetic diaphragm-type horns
are standard equipment on this model. Both horns
are secured to a mounting bracket. The mounting
bracket is secured with a screw to the back side of
the right extension of the radiator closure assembly,
just ahead of the right front wheel house and below
the front wheel house extension. The two horns are
connected in parallel. Each horn is grounded through
its wire harness connector and circuit to an eyelet
secured to the right inner fender shield near the bat-
tery, and receives battery feed through the closed
contacts of the horn relay.
The horns cannot be repaired or adjusted and, if
faulty or damaged, they must be individually
replaced.
OPERATION
Within the two halves of the molded plastic horn
housing are a flexible diaphragm, a plunger, an elec-
tromagnetic coil and a set of contact points. The dia-
phragm is secured in suspension around its
perimeter by the mating surfaces of the horn hous-
ing. The plunger is secured to the center of the dia-
phragm and extends into the center of the
electromagnet. The contact points control the current
flow through the electromagnet.
When the horn is energized, electrical current
flows through the closed contact points to the electro-
magnet. The resulting electromagnetic field draws
the plunger and diaphragm toward it until that
movement mechanically opens the contact points.
When the contact points open, the electromagnetic
field collapses allowing the plunger and diaphragm to
return to their relaxed positions and closing the con-
tact points again. This cycle continues repeating at a
very rapid rate producing the vibration and move-
ment of air that creates the sound that is directed
through the horn outlet.
DIAGNOSIS AND TESTING - HORN
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
(1) Disconnect the wire harness connector(s) from
the horn connector receptacle(s). Measure the resis-
tance between the ground circuit cavity of the horn(s)
wire harness connector(s) and a good ground. There
should be no measurable resistance. If OK, go to Step
2. If not OK, repair the open ground circuit to ground
as required.
(2) Check for battery voltage at the horn relay out-
put circuit cavity of the horn(s) wire harness connec-
tor(s). There should be zero volts. If OK, go to Step 3.
If not OK, repair the shorted horn relay output cir-
cuit or replace the faulty horn relay as required.
(3) Depress the horn switch. There should now be
battery voltage at the horn relay output circuit cavity
of the horn(s) wire harness connector(s). If OK,
replace the faulty horns. If not OK, repair the open
horn relay output circuit to the horn relay as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Raise and support the vehicle.
(3) Remove the lower front half of the inner liner
from the right front fender wheel house. (Refer to 23
- BODY/EXTERIOR/FRONT FENDER - REMOVAL).
(4) Reach through the front of the right front
fender wheel house opening to access and disconnect
the two right headlamp and dash wire harness con-
nectors from the horn connector receptacles (Fig. 1).
Be certain to disengage the connector lock tabs
before disconnecting them from the horn connector
receptacles.
(5) Remove the screw that secures the horn
mounting bracket to the right extension of the radi-
ator closure assembly.
WJHORN 8H - 3
HORN SYSTEM (Continued)

certain conditions or inputs to provide the vehicle
operator with an audible alert to supplement a visual
indication.
The EMIC circuitry operates on battery current
received through fused B(+) fuses in the Power Dis-
tribution Center (PDC) and the Junction Block (JB)
on a non-switched fused B(+) circuit, and on battery
current received through a fused ignition switch out-
put (run-start) fuse in the JB on a fused ignition
switch output (run-start) circuit. This arrangement
allows the EMIC to provide some features regardless
of the ignition switch position, while other features
will operate only with the ignition switch in the On
or Start positions. The EMIC circuitry is grounded
through two separate ground circuits of the instru-
ment panel wire harness. These ground circuits
receive ground through take outs of the instrument
panel wire harness with eyelet terminal connectors
that are secured by a nut to a ground stud located on
the floor panel transmission tunnel beneath the cen-
ter floor console, just forward of the Airbag Control
Module (ACM).
The EMIC also has a self-diagnostic actuator test
capability, which will test each of the PCI bus mes-
sage-controlled functions of the cluster by lighting
the appropriate indicators (except the airbag indica-
tor), sweeping the gauge needles across the gauge
faces from their minimum to their maximum read-
ings, and stepping the odometer display sequentially
from all zeros through all nines. (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). The self-diagnostic actuator test
can be initialized manually or using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the EMIC.
GAUGES
All gauges receive battery current through the
EMIC circuitry when the ignition switch is in the On
or Start positions. With the ignition switch in the Off
position battery current is not supplied to any
gauges, and the EMIC circuitry is programmed to
move all of the gauge needles back to the low end of
their respective scales. Therefore, the gauges do not
accurately indicate any vehicle condition unless the
ignition switch is in the On or Start positions. All of
the EMIC gauges, except the odometer, are air core
magnetic units. Two fixed electromagnetic coils are
located within each gauge. These coils are wrapped
at right angles to each other around a movable per-
manent magnet. The movable magnet is suspended
within the coils on one end of a pivot shaft, while the
gauge needle is attached to the other end of the
shaft. One of the coils has a fixed current flowingthrough it to maintain a constant magnetic field
strength. Current flow through the second coil
changes, which causes changes in its magnetic field
strength. The current flowing through the second coil
is changed by the EMIC circuitry in response to mes-
sages received over the PCI data bus. The gauge nee-
dle moves as the movable permanent magnet aligns
itself to the changing magnetic fields created around
it by the electromagnets.
The gauges are diagnosed using the EMIC self-di-
agnostic actuator test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the PCI data bus, and
the data bus message inputs to the EMIC that con-
trol each gauge requires the use of a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
Specific operation details for each gauge may be
found elsewhere in this service information.
VACUUM-FLUORESCENT DISPLAY
The Vacuum-Fluorescent Display (VFD) module is
soldered to the EMIC circuit board. The display is
active with the ignition switch in the On or Start
positions, and inactive when the ignition switch is in
any other position. The illumination intensity of the
VFD is controlled by the EMIC circuitry based upon
electronic dimming level messages received from the
BCM over the PCI data bus, and is synchronized
with the illumination intensity of other VFDs in the
vehicle. The BCM provides dimming level messages
based upon internal programming and inputs it
receives from the control knob and control ring on
the control stalk of the left (lighting) multi-function
switch on the steering column.
The VFD has several display capabilities including
odometer and trip odometer information. An odome-
ter/trip odometer switch on the EMIC circuit board is
used to control the display modes. This switch is
actuated manually by depressing the odometer/trip
odometer switch button that extends through the
lower edge of the cluster lens, just right of the speed-
ometer. Actuating this switch momentarily with the
ignition switch in the On position will toggle the
VFD between the odometer and trip odometer modes.
The EMIC microprocessor remembers which display
mode is active when the ignition switch is turned to
the Off position, and returns the display to that
mode when the ignition switch is turned On again.
Depressing the switch button for about two seconds
while the VFD is in the trip odometer mode will
reset the trip odometer value to zero. Holding this
switch depressed while turning the ignition switch
from the Off position to the On position will initiate
the EMIC self-diagnostic actuator test. Refer to the
appropriate diagnostic information for additional
details on this VFD function.
WJINSTRUMENT CLUSTER 8J - 5
INSTRUMENT CLUSTER (Continued)

INSTALLATION - CHMSL
(1) Connect the wire harness connector.
(2) Position the CHMSL on liftgate.
(3) Install the screws attaching the CHMSL to the
liftgate.
COMBINATION FLASHER
DESCRIPTION
The combination flasher is located in the Junction
Block (JB) (Fig. 6). The JB is located underneath the
driver side of the instrument panel outboard of the
steering column. The combination flasher is a smart
relay that functions as both the turn signal system
and the hazard warning system flasher. The combi-
nation flasher contains active electronic Integrated
Circuitry (IC) elements. This flasher is designed to
handle the current flow requirements of the factory-
installed lighting. If supplemental lighting is added
to the turn signal lamp circuits, such as when towing
a trailer with lights, the combination flasher will
automatically try to compensate to keep the flash
rate the same.The combination flasher has nine blade-type termi-
nals that connect it to the vehicle electrical system.
Refer to the appropriate wiring information.
Because of the active electronic elements within
the combination flasher, it cannot be tested with con-
ventional automotive electrical test equipment. If the
combination flasher is believed to be faulty, test the
turn signal system and hazard warning system cir-
cuits.(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING
- EXTERIOR - DIAGNOSIS AND TESTING - TURN
SIGNAL & HAZARD WARNING SYSTEM). The com-
bination flasher cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The combination flasher controls the following
inputs and outputs: B(+), fused ignition switch out-
put, left turn switch sense, right turn switch sense,
hazard switch sense, left front turn signal circuit,
right front turn signal circuit, left rear turn signal
circuit and right rear turn signal circuit. Constant
battery voltage is supplied to the flasher so that it
can perform the hazard warning function, and igni-
tion switched battery voltage is supplied for the turn
signal function. However, when the flasher is idle no
current is drawn through the module. The unit does
not become active until it is provided a signal ground
from the turn signal switch, hazard warning switch
or the Body Control Module (BCM).
The IC within the combination flasher (Fig. 7) con-
tains the logic that controls the flasher operation and
the flash rate. When a bulb is burnt out, or when a
circuit for a lamp is open, the turn signal flash rate
will increase. However, an open lamp circuit or burnt
out bulb does not change the hazard warning flash
rate.
Fig. 6 Combination Flasher
1 - COMBINATION FLASHER
2 - JUNCTION BLOCK
WJLAMPS/LIGHTING - EXTERIOR 8L - 7
CENTER HIGH MOUNTED STOP LAMP (Continued)

(4) Install airbag module. Refer to Group 8M, Pas-
sive Restraint Systems.
(5) Connect negative battery cable.
VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is a plastic storage tank con-
nected to an engine vacuum source by vacuum lines.
OPERATION
The vacuum reservoir is used to supply the vac-
uum needed to maintain proper speed control opera-
tion when engine vacuum drops, such as in climbing
a grade while driving. A one-way check valve is used
in the vacuum line between the reservoir and the
vacuum source. This check valve is used to trap
engine vacuum in the reservoir. On certain vehicle
applications, this reservoir is shared with the heat-
ing/air-conditioning system. The vacuum reservoir
cannot be repaired and must be replaced if faulty.
DIAGNOSIS AND TESTING - VACUUM
RESERVOIR
(1) Disconnect vacuum hose at speed control servo
and install a vacuum gauge into the disconnected
hose.
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum is less than ten inches of mercury,
determine source of leak. Check vacuum line to
engine for leaks. Also check actual engine intake
manifold vacuum. If manifold vacuum does not meet
this requirement, check for poor engine performance
and repair as necessary.
(4) If vacuum line to engine is not leaking, check
for leak at vacuum reservoir. To locate and gain
access to reservoir, refer to Vacuum Reservoir Remov-
al/Installation in this group. Disconnect vacuum line
at reservoir and connect a hand-operated vacuum
pump to reservoir fitting. Apply vacuum. Reservoir
vacuum should not bleed off. If vacuum is being lost,
replace reservoir.
(5) Verify operation of one-way check valve and
check it for leaks.
(a) Locate one-way check valve. The valve is
located in vacuum line between vacuum reservoir
and engine vacuum source. Disconnect vacuum
hoses (lines) at each end of valve.
(b) Connect a hand-operated vacuum pump to
reservoir end of check valve. Apply vacuum. Vac-
uum should not bleed off. If vacuum is being lost,
replace one-way check valve.
(c) Connect a hand-operated vacuum pump to
vacuum source end of check valve. Apply vacuum.
Vacuum should flow through valve. If vacuum is
not flowing, replace one-way check valve. Seal the
fitting at opposite end of valve with a finger and
apply vacuum. If vacuum will not hold, diaphragm
within check valve has ruptured. Replace valve.
REMOVAL
The vacuum reservoir is located in the right/front
corner of the vehicle behind the front bumper fascia
(Fig. 8).
(1) Remove front bumper and grill assembly.
(2) Remove 1 support bolt near front of reservoir
(Fig. 8).
(3) Remove 2 reservoir mounting bolts.
(4) Remove reservoir from vehicle to gain access to
vacuum hose (Fig. 9). Disconnect vacuum hose from
reservoir fitting at rear of reservoir.
Fig. 7 Speed Control Switches
1 - MOUNTING SCREW
2 - SPEED CONTROL SWITCHES
8P - 8 SPEED CONTROLWJ
SWITCH (Continued)

WASHER SYSTEM
The washer system components should be
inspected periodically, not just when washer perfor-
mance problems are experienced. This inspection
should include the following points:
(1) Check for ice or other foreign material in the
washer reservoir. If contaminated, clean and flush
the washer system. (Refer to 8 - ELECTRICAL/
FRONT WIPERS/WASHERS - CLEANING).
(2) Inspect the washer plumbing for pinched, leak-
ing, deteriorated, or incorrectly routed hoses and
damaged or disconnected hose fittings. Replace dam-
aged or deteriorated hoses and hose fittings. Leaking
washer hoses can sometimes be repaired by cutting
the hose at the leak and splicing it back together
using an in-line connector fitting. Similarly, sections
of deteriorated hose can be cut out and replaced by
splicing in new sections of hose using in-line connec-
tor fittings. Whenever routing a washer hose or a
wire harness containing a washer hose, it must be
routed away from hot, sharp, or moving parts. Also,
sharp bends that might pinch the washer hose must
be avoided.
FRONT CHECK VALVE
DESCRIPTION
A front washer system check valve is standard
equipment on this model. The front check valve is
integral to the front washer nozzle plumbing wye fit-
ting located in the cowl plenum beneath the cowl ple-
num cover/grille panel near the base of the
windshield. The check valve consists of a molded
plastic body with a round center section. Three
barbed hose nipples are formed in a wye configura-
tion on the outside circumference of the center sec-
tion of the valve body. Within the check valve body, a
small check valve operated by a small coiled spring
restricts flow through the unit until the valve is
unseated by a predetermined inlet fluid pressure.
The front check valve cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced.
OPERATION
The front check valve provides more than one func-
tion in this application. It serves as a wye connector
fitting between the cowl grille panel and washer noz-
zle sections of the front washer supply hose. It also
prevents washer fluid from draining out of the front
washer supply hoses back to the washer reservoir.
This drain-back would result in a lengthy delay from
when the front washer switch is actuated until
washer fluid was dispensed through the front washer
nozzles, because the front washer pump would have
to refill the front washer plumbing from the reservoir
to the nozzles. Finally, the front check valve prevents
washer fluid from siphoning through the front
washer nozzles after the front washer system is
turned Off. When the front washer pump pressurizes
and pumps washer fluid from the reservoir through
the front washer plumbing, the fluid pressure over-
rides the spring pressure applied to the check valve
and unseats the valve, allowing washer fluid to flow
toward the front washer nozzles. When the front
washer pump stops operating, spring pressure seats
the check valve and fluid flow in either direction
within the front washer plumbing is prevented.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the wiper arms from the wiper pivots.
(Refer to 8 - ELECTRICAL/FRONT WIPERS/WASH-
ERS/FRONT WIPER ARMS - REMOVAL).
(3) Open the hood and pull the hood to plenum
seal off of the forward flanges of the cowl grille cover
and the plenum panel.
Fig. 2 Wiper Blade Inspection
1 - WORN OR UNEVEN EDGES
2 - ROAD FILM OR FOREIGN MATERIAL DEPOSITS
3 - HARD, BRITTLE, OR CRACKED
4 - DEFORMED OR FATIGUED
5 - SPLIT
6 - DAMAGED SUPPORT COMPONENTS
WJFRONT WIPERS/WASHERS 8R - 9
FRONT WIPERS/WASHERS (Continued)

(3) Insert the hook formation on the tip of the
wiper arm through the opening in the wiper blade
superstructure ahead of the wiper blade pivot block/
latch unit far enough to engage the pivot block with
the hook (Fig. 10).
(4) Slide the wiper blade pivot block/latch up into
the hook formation on the tip of the wiper arm until
the latch release tab snaps into its locked position.
Latch engagement will be accompanied by an audible
click.
(5) Gently lower the wiper blade onto the glass.
FRONT WIPER MODULE
DESCRIPTION
The front wiper module is secured with four screws
through rubber isolators to the cowl plenum panel
beneath the cowl plenum cover/grille panel (Fig. 11).
The ends of the wiper pivot shafts that protrude
through dedicated openings in the cowl plenum cov-
er/grille panel to drive the wiper arms and blades are
the only visible components of the front wiper mod-
ule. The front wiper module consists of the following
major components:
²Bracket- The front wiper module bracket con-
sists of a long tubular steel main member that has a
stamped pivot bracket formation near each end
where the two wiper pivots are secured. A stamped
steel mounting plate for the wiper motor is secured
with welds near the center of the main member.
²Crank Arm- The front wiper motor crank arm
is a stamped steel unit with a slotted hole on the
driven end that is secured to the wiper motor outputshaft with a nut, and a ball stud secured to the drive
end.
²Linkage- Two stamped steel drive links con-
nect the wiper motor crank arm to the pivot lever
arms. The passenger side drive link has a plastic
socket-type bushing on each end. The driver side
drive link has a plastic socket-type bushing on one
end, and a plastic sleeve-type bushing on the other
end. The socket-type bushing on one end of each
drive link is snap-fit over the ball stud on the lever
arm of its respective pivot. The driver side drive link
sleeve-type bushing end is then fit over the motor
crank arm ball stud, and the other socket-type bush-
ing of the passenger side drive link is snap-fit over
the exposed end of the wiper motor crank arm ball
stud.
²Motor- The front wiper motor is secured with
three screws to the motor mounting plate near the
center of the wiper module bracket. The wiper motor
output shaft passes through a hole in the module
bracket, where a nut secures the wiper motor crank
arm to the motor output shaft. The two-speed perma-
nent magnet wiper motor features an integral trans-
mission, an internal park switch, and an internal
automatic resetting circuit breaker.
²Pivots- The two front wiper pivots are secured
to the ends of the wiper module bracket. The crank
arms that extend from the bottom of the pivot shafts
each have a ball stud on their end. The upper end of
each pivot shaft where the wiper arms will be fas-
tened each has an externally serrated drum with a
threaded stud secured to it.
The front wiper module cannot be adjusted or
repaired. If any component of the module is faulty or
damaged, the entire front wiper module unit must be
replaced. The reinforcement bracket and stud plate
are available for service replacement.OPERATION
The front wiper module operation is controlled by
the battery current inputs received by the wiper
motor from the wiper on/off and wiper high/low
relays. The wiper motor speed is controlled by cur-
rent flow to either the low speed or the high speed
set of brushes. The park switch is a single pole, sin-
gle throw, momentary switch within the wiper motor
that is mechanically actuated by the wiper motor
transmission components. The park switch alter-
nately closes the wiper park switch sense circuit to
ground or to battery current, depending upon the
position of the wipers on the glass. This feature
allows the motor to complete its current wipe cycle
after the wiper system has been turned Off, and to
park the wiper blades in the lowest portion of the
wipe pattern. The automatic resetting circuit breaker
protects the motor from overloads. The wiper motor
Fig. 11 Front Wiper Module
1 - FRONT WIPER MODULE
2 - SCREW (4)
3 - WIRE HARNESS CONNECTOR
4 - LOWER COWL PLENUM PANEL
8R - 16 FRONT WIPERS/WASHERSWJ
FRONT WIPER BLADE (Continued)