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Jeep Grand Cherokee WJ. Manual - part 152

connection to the two motor terminals will cause the
power lock motor plunger to move in one direction.
Reversing the current through these same two con-
nections will cause the power lock motor plunger to
move in the opposite direction.

DIAGNOSIS AND TESTING

POWER LOCK SYSTEM

Following are tests that will help to diagnose the

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

The most reliable, efficient, and accurate means to

diagnose the power lock 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 receiving the
proper messages on the PCI data bus, and that the
power lock motors are being sent the proper hard
wired outputs by the door modules for them to per-
form their power lock system functions.

For complete circuit diagrams, refer to Power

Door Locks in the Contents of Group 8W - Wiring
Diagrams.

PRELIMINARY DIAGNOSIS

As a preliminary diagnosis for the power lock sys-

tem, note the system operation while you actuate
both the Lock and Unlock functions with the power
lock switches and with the Remote Keyless Entry
(RKE) transmitter. Then, proceed as follows:

• If the entire power lock system fails to function

with either the power lock switches or the RKE
transmitter, check the fused B(+) fuse in the Power
Distribution Center. If the fuse is OK, refer to Door
Module in the Diagnosis and Testing section of this
group.

• If the power lock system functions with both

power lock switches, but not with the RKE transmit-
ter, refer to Remote Keyless Entry System in the
Remote Keyless Entry System section of this group.

• If the power lock system functions with the RKE

transmitter, but not with one or both power lock
switches, refer to Door Module in the Diagnosis and
Testing section of this group.

• If the driver side power lock switch operates

only the driver side front door power lock motor, but
all other power lock motors operate with the passen-
ger side power lock switch or the RKE transmitter,

use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to diagnose the Programmable Com-
munications Interface (PCI) data bus.

• If only one power lock motor to operate with

both power lock switches and the RKE transmitter,
refer to Power Lock Motor in the Diagnosis and
Testing section of this group.

DOOR MODULE

NOTE: The following tests may not prove conclu-
sive in the diagnosis of this component. The most
reliable, efficient, and accurate means to diagnose
this system involves the use of a DRB scan tool
and the proper Diagnostic Procedures manual.

Remember, the Driver Door Module (DDM) cir-

cuitry controls the output to the driver side front
door power lock motor. The Passenger Door Module
(PDM) circuitry controls the output to the power lock
motors for the remaining doors and the liftgate. For
complete circuit diagrams, refer to Power Door
Locks in the Contents of Group 8W - Wiring Dia-
grams.

(1) Disconnect and isolate the battery negative

cable. Remove the front door trim panel. Go to Step
2.

(2) Check the 15-way door wire harness connector

for the door module to see that it is fully seated in
the door module connector receptacle. If OK, go to
Step 3. If not OK, install the door wire harness con-
nector in the door module connector receptacle prop-
erly.

(3) Disconnect the 15-way door wire harness con-

nector for the door module from the door module con-
nector receptacle. Check for continuity between the
ground circuit cavity of the 15-way door wire harness
connector for the door module and a good ground.
There should be continuity. If OK, go to Step 4. If not
OK, repair the open ground circuit to ground as
required.

(4) Connect the battery negative cable. Check for

battery voltage at the fused B(+) circuit cavity of the
15-way door wire harness connector for the door
module. If OK, go to Step 5. If not OK, repair the
open fused B(+) circuit to the Power Distribution
Center (PDC) fuse as required.

(5) Disconnect and isolate the battery negative

cable. Check for continuity between the door lock
driver circuit cavity of the 15-way door wire harness
connector for the door module and a good ground.
Repeat the check for the door unlock driver circuit.
In each case there should be no continuity. If OK, go
to Step 6. If not OK, repair the shorted door lock or
unlock driver circuit as required.

(6) Disconnect the door or liftgate wire harness

connector from the inoperative power lock motor wire

8P - 4

POWER LOCK SYSTEMS

DESCRIPTION AND OPERATION (Continued)

harness connector. Check for continuity between the
door lock driver circuit cavities in the door or liftgate
wire harness connector for the inoperative power lock
motor and the 15-way door wire harness connector
for the door module. Repeat the check for the door
unlock driver circuit. In each case, there should be
continuity. If OK, go to Step 7. If not OK, repair the
open door lock or unlock driver circuit as required.

(7) Reconnect the 15-way door wire harness con-

nector to the door module connector receptacle. Con-
nect the battery negative cable. Go to Step 8.

(8) Connect the probes of a reversible DC digital

voltmeter to the door lock and unlock driver circuit
cavities of the door or liftgate wire harness connector
for the inoperative power lock motor. Observe the
voltmeter while actuating the power lock switch in
the lock and unlock directions. There should be a
short 12-volt voltage spike as the switch is moved to
both the lock and unlock positions, and no voltage in
the neutral position. If OK, refer to Power Lock
Motor in the Diagnosis and Testing section of this
group. If not OK, replace the faulty door module.

POWER LOCK MOTOR

Remember, the Driver Door Module (DDM) cir-

(1) Check each power lock motor for correct opera-

tion while moving the power lock switch to both the
Lock and Unlock positions. If all of the power lock
motors are inoperative, go to Step 2. If one power
lock motor is inoperative, go to Step 3.

(2) If all of the power lock motors except the driver

side front door are inoperative, the problem may be
caused by one shorted motor. Disconnecting a shorted
power lock motor from the power lock circuit will
allow the good power lock motors to operate. Discon-
nect each PDM-controlled power lock motor wire har-
ness connector, one at a time, and recheck both the
lock and unlock functions by operating the power
lock switch. If all of the PDM-controlled power lock
motors are still inoperative after the above test,
check for a short or open circuit between the power
lock motors and the PDM. If disconnecting one power
lock motor causes the other motors to become func-
tional, go to Step 3 to test the power lock motor that
was last disconnected.

(3) Once it is determined which power lock motor

is inoperative, that motor can be tested as follows.
Disconnect the door or liftgate wire harness connec-
tor at the inoperative power lock motor. Apply 12

volts to the lock and unlock driver circuit cavities of
the power lock motor connector to check its operation
in one direction. Reverse the polarity to check the
operation in the other direction. If OK, repair the
shorted or open circuits to the DDM or PDM as
required. If not OK, replace the faulty power lock
motor.

REMOVAL AND INSTALLATION

DOOR MODULE

REMOVAL

(1) Disconnect and isolate the battery negative

cable.

(2) Remove the trim panel from the front door.

Refer to Front Door Trim Panel in the Removal
and Installation section of Group 23 - Body for the
procedures.

(3) Remove the five screws that secure the door

module to the back of the front door trim panel (Fig.
1).

(4) Remove the door module from the front door

trim panel.

INSTALLATION

(1) Position the door module to the front door trim

panel.

Fig. 1 Door Module Remove/Install

1 – FRONT DOOR TRIM PANEL
2 – SCREW (5)
3 – DOOR MODULE

POWER LOCK SYSTEMS

8P - 5

DIAGNOSIS AND TESTING (Continued)

(2) Install and tighten the five screws that secure

the door module to the back of the front door trim
panel. Tighten the screws to 2.2 N·m (20 in. lbs.).

(3) Install the trim panel onto the front door. Refer

to Front Door Trim Panel in the Removal and

Installation section of Group 23 - Body for the proce-
dures.

(4) Reconnect the battery negative cable.

8P - 6

POWER LOCK SYSTEMS

REMOVAL AND INSTALLATION (Continued)

LIFTGATE FLIP-UP GLASS POWER RELEASE SYSTEM

TABLE OF CONTENTS

page

DESCRIPTION AND OPERATION

LIFTGATE FLIP-UP GLASS POWER RELEASE

SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

DIAGNOSIS AND TESTING

LIFTGATE FLIP-UP GLASS POWER RELEASE

SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

REMOVAL AND INSTALLATION

LIFTGATE FLIP-UP GLASS POWER RELEASE

SYSTEM COMPONENTS . . . . . . . . . . . . . . . . . . 8

DESCRIPTION AND OPERATION

LIFTGATE FLIP-UP GLASS POWER RELEASE
SYSTEM

DESCRIPTION

A power operated liftgate flip-up glass release sys-

tem ids standard factory installed equipment on this
model. The liftgate flip-up glass power release system
allows the flip-up glass latch to be released electri-
cally by depressing a switch located on the bottom of
the liftgate license plate lamp housing unit, above
the license plate on the outside of the liftgate.

The liftgate flip-up glass release system operates

on non-switched battery current supplied through a
fuse in the junction block so that the system remains
functional, regardless of the ignition switch position.
However, a limit switch that is integral to the liftgate
latch actuator unit opens to prevent the flip-up glass
latch from being actuated when the liftgate latch is
locked.

The liftgate flip-up glass power release system

includes the following components:

• Liftgate flip-up glass limit switch

• Liftgate flip-up glass release motor

• Liftgate flip-up glass release switch.
Refer to Power Door Locks in the Contents of

Group 8W - Wiring Diagrams for complete circuit
diagrams.

OPERATION

When the liftgate mounted flip-up glass release

switch is depressed, battery current is directed to the
electric release motor that is integral to the flip-up
glass latch located inside the liftgate. When the
release motor is energized the latch releases and the
flip-up glass can be opened. A liftgate flip-up glass
limit switch is integral to the liftgate latch actuator
mechanism. The limit switch automatically enables
or disables the liftgate flip-up glass power release cir-
cuitry, depending upon the position of the liftgate

latch lock mechanism. When the liftgate latch is
unlocked, the limit switch closes and battery current
is available at the release switch. When the liftgate
latch is locked, the limit switch opens, and the
release switch is disabled.

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

more information on the features, use and operation
of the liftgate flip-up glass power release system.

DIAGNOSIS AND TESTING

LIFTGATE FLIP-UP GLASS POWER RELEASE
SYSTEM

For complete circuit diagrams, refer to Power

Door Locks in Group 8W - Wiring Diagrams.

(1) Check the fused B(+) fuse in the junction block.

If OK, go to Step 2. If not OK, repair the shorted cir-
cuit or component as required and replace the faulty
fuse.

(2) Check for battery voltage at the fused B(+) fuse

in the junction block. If OK, go to Step 3. If not OK,
repair the open fused B(+) circuit to the Power Dis-
tribution Center (PDC) as required.

(3) Disconnect the liftgate wire harness connector

from the liftgate flip-up glass limit switch. Check for
battery voltage at the fused B(+) circuit cavity of the
liftgate wire harness connector for the flip-up glass
limit switch. If OK, go to Step 4. If not OK, repair
the open fused B(+) circuit to the junction block fuse
as required.

(4) Check for continuity between the two terminals

of the liftgate flip-up glass limit switch. There should
be continuity with the liftgate latch unlocked, and no
continuity with the latch locked. If OK, go to Step 5.
If not OK, replace the faulty liftgate flip-up glass
limit switch (liftgate latch actuator unit).

(5) Disconnect the liftgate wire harness connector

from the liftgate flip-up glass release switch. With
the liftgate latch unlocked, check for battery voltage
at the liftgate flip-up glass limit switch output circuit
cavity of the liftgate wire harness connector for the

POWER LOCK SYSTEMS

8P - 7

Content .. 150 151 152 153 ..