Jeep Grand Cherokee WJ. Manual - part 125

WINDSHIELD WIPER ARM AND BLADE

DESCRIPTION

All Grand Cherokee models have two 52.50 centi-

meter (20.67 inch) long windshield wiper blades with
non-replaceable rubber elements (squeegees). The
center of the wiper blade has a molded plastic pivot
block with an integral latch that is secured in a
U-shaped formation on the end of the wiper arm.

The spring-loaded wiper arms feature over-center

hinges. The spring tension of the wiper arm controls
the pressure applied to the wiper blade on the glass.
The over-center hinges allow the blades to stand off
of the glass for easy snow removal and cleaning of
the glass and squeegees.

The windshield wiper arms are secured by a nut to

the threaded studs on the two wiper pivots near the
base of the windshield. A molded plastic cap fits over
the nut for a neat appearance. Alignment marks
molded into the windshield near the base of the glass
ensure accurate wiper arm and blade installation.

Caution should be exercised to protect the rubber

wiper blade squeegees from any petroleum-based
cleaners or contaminants, which will rapidly deterio-
rate the rubber. Also, wiper squeegees exposed to the
elements for a long time tend to lose their wiping
effectiveness.

Periodic cleaning of the wiper blade squeegees is

suggested to remove deposits of salt and road film.
The wiper blades, arms, and windshield glass should
be cleaned with a sponge or cloth and windshield
washer fluid, a mild detergent, or a non-abrasive
cleaner. If the squeegees are damaged, worn, or con-
taminated the wiper blades should be replaced.

The wiper blades and wiper arms are available for

service replacement. The wiper arms and wiper
blades cannot be adjusted or repaired. If they are
faulty or damaged, they must be replaced.

OPERATION

When the wiper blades are moved back and forth

across the windshield glass, the rubber squeegees of
the wiper blade clear the glass of rain, snow and
other materials that can obstruct visibility. The
spring loaded hinges of the wiper arms determine the
pressure applied to the wiper blade on the glass. The
multiple bridge formations of the wiper blade help to
distribute the wiper arm spring pressure evenly over
the length of the squeegee, and allow the squeegee to
conform to the contour of the glass.

WINDSHIELD WIPER MOTOR, PIVOT AND
LINKAGE MODULE

DESCRIPTION

The windshield wiper motor, pivot and linkage

module is secured with four screws through rubber
isolators to the cowl plenum panel beneath the cowl
plenum cover/grille panel. The two-speed permanent
magnet windshield wiper motor has an integral
transmission and park switch. The park switch opens
and closes as the wiper motor operates. When the
wipers are up off the base of the windshield, the park
switch is closed; and, when the wipers are near the
base of the windshield (parked), the park switch is
open. The wiper motor is secured below the center of
the module bracket with three screws. The wiper
motor output shaft passes through a clearance hole,
where a nut secures the wiper motor crank arm to
the motor output shaft above the module bracket.

The two wiper pivots are secured at the ends of the

module bracket. The two wiper pivot lever arms and
the wiper motor crank arm each have ball studs on
their ends. The motor crank arm ball stud is the
longer of the three. Two drive links connect the
motor crank arm to the pivot lever arms. The passen-
ger 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 bush-
ing 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 bushing of the passenger side drive link
is snap-fit over the exposed end of the motor crank
arm ball stud.

The wiper motor, pivots, linkage, bushings, motor

crank arm and mounting bracket are only serviced as
a complete unit. If any part of this unit is faulty or
damaged, the entire wiper motor pivot and linkage
module must be replaced.

OPERATION

The windshield wiper motor speed is controlled by

current flow to the proper set of brushes. When the
wiper motor is turned on, the park switch provides
the Body Control Module (BCM) with a pulse signal
that allows the BCM wiper system logic to monitor
the number and frequency of the wipe cycles. When
the wiper motor is turned off, the closed park switch
(wipers up) provides battery voltage to the wiper
motor until the park switch opens (wipers down or
parked). The wiper motor crank arm, linkage and
pivots convert the rotary action of the wiper motor
output shaft to the back and forth wiping motion of
the wiper arms and blades.

8K - 6

WIPER AND WASHER SYSTEMS

DESCRIPTION AND OPERATION (Continued)

WIPER SWITCH AND WASHER SWITCH

DESCRIPTION

All of the windshield and rear wiper and washer

system switches are integral to the right (wiper)
multi-function switch unit, which is secured to the
right side of the multi-function switch mounting
housing at the top of the steering column (Fig. 1).
The only visible part of the right multi-function
switch is the control stalk that extends from the
right side of the steering column. The right multi-
function switch control stalk has both nomenclature
and international control symbols on it, which iden-
tify its many functions. The remainder of the right
multi-function switch is concealed beneath the steer-
ing column shrouds.

The wiper and washer system switches cannot be

repaired. If these switches or any other circuit or
component of the right multi-function switch unit is
faulty or damaged, the entire right multi-function
switch unit must be replaced.

OPERATION

A rotary switch knob on the end of the right multi-

function switch control stalk is rotated to select the
desired windshield wiper continuous speed setting or
one of five intermittent wipe mode delay intervals.
The control stalk is pulled toward the driver to acti-
vate the windshield washer system. The control stalk
is moved downward to activate the windshield wiper
mist function.

A rotary switch ring on the right multi-function

switch stalk just below the windshield wiper switch
knob controls the rear wiper system functions. The

switch ring is rotated to select the rear wiper delay
or continuous wipe modes. The control stalk is
pushed away from the driver, toward the instrument
panel to activate the rear washer system.

See the owner’s manual in the vehicle glove box for

more information on the features, use and operation
of the wiper and washer (right multi-function)
switches.

WIPER HIGH/LOW RELAY

DESCRIPTION

The wiper high/low relay is a electromechanical

device that switches battery current from the wiper
motor low speed coil windings to the high speed coil
windings when the wiper and washer (right multi-
function) switch grounds the relay coil. The wiper
high/low relay is located in the Power Distribution
Center (PDC) in the engine compartment. See the
fuse and relay layout label affixed to the inside sur-
face of the PDC cover for wiper high/low relay iden-
tification and location.

The wiper high/low relay is a International Stan-

dards Organization (ISO) micro-relay. Relays con-
forming to the ISO specifications have common
physical dimensions, current capacities, terminal pat-
terns, and terminal functions. The ISO micro-relay
terminal functions are the same as a conventional
ISO relay. However, the ISO micro-relay terminal
pattern (or footprint) is different, the current capac-
ity is lower, and the physical dimensions are smaller
than those of the conventional ISO relay.

The wiper high/low relay cannot be repaired or

adjusted and, if faulty or damaged, it must be
replaced.

OPERATION

The ISO relay consists of an electromagnetic coil, a

resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.

When the electromagnetic coil is de-energized,

spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the
relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.

Fig. 1 Right (Wiper) Multi-Function Switch

1 – CONTROL STALK
2 – REAR WIPER CONTROL
3 – FRONT WIPER CONTROL
4 – RIGHT (WIPER) MULTI-FUNCTION SWITCH

WIPER AND WASHER SYSTEMS

8K - 7

DESCRIPTION AND OPERATION (Continued)

WIPER ON/OFF RELAY

DESCRIPTION

The wiper on/off relay is a electromechanical device

that switches battery current to the wiper high/low
relay when the Body Control Module (BCM) grounds
the relay coil. The wiper on/off relay is located in the
Power Distribution Center (PDC) in the engine com-
partment. See the fuse and relay layout label affixed
to the inside surface of the PDC cover for wiper
on/off relay identification and location.

The wiper on/off relay is a International Standards

Organization (ISO) micro-relay. Relays conforming to
the ISO specifications have common physical dimen-
sions, current capacities, terminal patterns, and ter-
minal

functions.

The

ISO

micro-relay

terminal

functions are the same as a conventional ISO relay.
However, the ISO micro-relay terminal pattern (or
footprint) is different, the current capacity is lower,
and the physical dimensions are smaller than those
of the conventional ISO relay.

The wiper on/off relay cannot be repaired or

adjusted and, if faulty or damaged, it must be
replaced.

OPERATION

The ISO relay consists of an electromagnetic coil, a

When the electromagnetic coil is de-energized,

DIAGNOSIS AND TESTING

WINDSHIELD WIPER SYSTEM

Following are tests that will help to diagnose the

hard wired components and circuits of the windshield
wiper system. However, these tests may not prove
conclusive in the diagnosis of this system. In order to
obtain conclusive testing of the windshield wiper sys-
tem, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the windshield wiper system components must be
checked.

The most reliable, efficient, and accurate means to

diagnose the windshield wiper system requires the
use of a DRB scan tool and the proper Diagnostic
Procedures manual. The DRB scan tool can provide
confirmation that the PCI data bus is functional, that
all of the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus, and
that the wiper on/off and wiper high/low relays are
being sent the proper hard wired outputs by the
Body Control Module (BCM) for them to perform
their windshield wiper system functions.

For complete circuit diagrams, refer to Wipers in

the Contents of Group 8W - Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,

REFER

GROUP

PASSIVE

RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING

WHEEL,

STEERING

COLUMN,

INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

(1) Check the fused ignition switch output (run/ac-

cessory) fuse in the junction block. If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse.

(2) Turn the ignition switch to the On position.

Check for battery voltage at the fused ignition switch
output (run/accessory) fuse in the junction block. If
OK, go to Step 3. If not OK, repair the open fused
ignition switch output (run/accessory) circuit to the
ignition switch as required.

(3) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.
Disconnect the instrument panel wire harness con-
nector from the wiper and washer (right multi-func-
tion) switch connector receptacle. Connect the battery
negative cable. Turn the ignition switch to the On
position. Check for battery voltage at the fused igni-
tion switch output circuit cavity of the instrument
panel wire harness connector for the wiper and
washer switch. If OK, go to Step 4. If not OK, repair
the open circuit to the junction block fuse as
required.

(4) Disconnect the 22-way instrument panel wire

harness connector from the Body Control Module
(BCM). Check for continuity between the windshield
wiper switch return circuit cavity of the instrument
panel wire harness connector for the wiper and
washer switch and a good ground. There should be
no continuity. If OK, go to Step 5. If not OK, repair
the shorted windshield wiper switch return circuit to
the BCM as required.

(5) Check for continuity between the windshield

wiper switch return circuit cavities of the instrument

8K - 8

WIPER AND WASHER SYSTEMS

DESCRIPTION AND OPERATION (Continued)

panel wire harness connector for the wiper and
washer switch and the 22-way instrument panel wire
harness connector for the BCM. There should be con-
tinuity. If OK, go to Step 6. If not OK, repair the
open windshield wiper switch return circuit to the
BCM as required.

(6) Check for continuity between the windshield

wiper switch mux circuit cavity of the instrument
panel wire harness connector for the wiper and
washer switch and a good ground. There should be
no continuity. If OK, go to Step 7. If not OK, repair
the shorted windshield wiper switch mux circuit to
the BCM as required.

(7) Check for continuity between the windshield

wiper switch mux circuit cavities of the instrument
panel wire harness connector for the wiper and
washer switch and the 22-way instrument panel wire
harness connector for the BCM. There should be con-
tinuity. If OK, reconnect the 22-way instrument
panel wire harness connector to the BCM connector
receptacle and go to Step 8. If not OK, repair the
open windshield wiper switch mux circuit to the
BCM as required.

(8) Refer to Wiper and Washer Switch in the

Diagnosis and Testing section of this group. If the
wiper and washer switch tests OK, reconnect the
instrument panel wire harness connector to the
wiper and washer switch connector receptacle and go
to Step 9. If the wiper and washer switch does not
test OK, replace the faulty wiper and washer switch.

(9) If the problem being diagnosed is that the

wiper blades do not park, but all other functions are
OK, go to Step 10. If the problem being diagnosed is
that the wipers will operate in low speed when an
intermittent delay is selected and the wiper blades
do not park, go to Step 11. If the problem being diag-
nosed is no wiper operation in any mode, go to Step
14. If the problem being diagnosed is that the wipers
will not operate in high speed, go to Step 18.

(10) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.
Backprobe the fused ignition switch output (V6) cir-
cuit cavity of the left headlamp and dash wire har-
ness

connector

the

windshield

wiper

motor.

Reconnect the battery negative cable. Turn the igni-
tion switch to the On position. Check for battery volt-
age. If OK, go to Step 11. If not OK, repair the open
fused ignition switch output (V6) circuit to the junc-
tion block wiper system circuit breaker as required.

(11) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.
Disconnect the left headlamp and dash wire harness
connector from the windshield wiper motor connector
receptacle. Disconnect the 52-way (C2) instrument
panel wire harness connector from the junction block
connector receptacle. Check for continuity between

the wiper park switch sense circuit cavity of the left
headlamp and dash wire harness connector for the
windshield wiper motor and a good ground. There
should be no continuity. If OK, go to Step 12. If not
OK, repair the shorted wiper park switch sense cir-
cuit as required.

(12) Check for continuity between the wiper park

switch sense circuit cavities of the left headlamp and
dash wire harness connector for the windshield wiper
motor and the 52-way (C2) instrument panel wire
harness connector for the junction block. There
should be continuity. If OK reconnect the 52-way (C2)
instrument panel wire harness connector to the junc-
tion block connector receptacle and go to Step 13. If
not OK, repair the open wiper park switch sense cir-
cuit as required.

(13) Reconnect the left headlamp and dash wire

harness connector to the windshield wiper motor con-
nector receptacle. Reconnect the battery negative
cable. Turn the ignition switch to the On position.
Backprobe the wiper park switch sense circuit cavity of
the left headlamp and dash wire harness connector at
the windshield wiper motor. Check for battery voltage.
With the wiper switch in the Low or High position, the
meter should switch between battery voltage and zero
volts. Turn the wiper switch to the Off position and the
meter should read battery voltage until the wiper
blades park, and then read a steady zero volts. If OK,
use a DRB scan tool and the proper Diagnostic Proce-
dures manual to diagnose the BCM. If not OK, replace
the faulty windshield wiper motor.

(14) Backprobe the ground circuit cavity of the left

headlamp and dash wire harness connector at the
windshield wiper motor. Check for continuity to a
good ground. There should be continuity. If OK, go to
Step 15. If not OK, repair the open ground circuit to
ground as required.

(15) Remove the wiper system circuit breaker from

the junction block. Reconnect the battery negative
cable. Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/accessory) cavity for the wiper system
circuit breaker in the junction block. If OK, go to
Step 16. If not OK, repair the open fused ignition
switch output (run/accessory) circuit to the ignition
switch as required.

(16) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.
Install the wiper system circuit breaker in the junc-
tion block. Reconnect the battery negative cable.
Turn the ignition switch to the On position. Check
for battery voltage at the fused ignition switch out-
put (V6) circuit cavity for the wiper system circuit
breaker in the junction block. If OK, go to Step 17. If
not OK, replace the faulty wiper system circuit
breaker.

WIPER AND WASHER SYSTEMS

8K - 9

DIAGNOSIS AND TESTING (Continued)

Content .. 123 124 125 126 ..