2002 JEEP GRAND CHEROKEE grounds

DIAGNOSIS AND TESTING - SIDEVIEW
MIRROR
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
BOTH MIRRORS INOPERATIVE
(1) Check the operation of the power lock switch
on the driver side front door. If all of the doors lock
and unlock, replace the faulty Driver Door Module
(DDM). If not OK, go to Step 2.
(2) Check the operation of the power lock switch
on the passenger side front door. If all of the doors
lock and unlock, replace the faulty DDM. If not OK,
go to Step 3.
(3) Check the fused B(+) fuse in the Power Distri-
bution Center (PDC). If OK, go to Step 4. If not OK,
repair the shorted circuit or component as required
and replace the faulty fuse.
(4) Check for battery voltage at the fused B(+) fuse
in the PDC. If OK, go to Step 5. If not OK, repair the
open fused B(+) circuit to the battery as required.
(5) Disconnect and isolate the battery negative
cable. Remove the trim panel from the driver side
front door. Disconnect the 15-way door wire harness
connector from the DDM connector receptacle. Check
for continuity between the ground circuit cavity of
the 15-way door wire harness connector for the DDM
and a good ground. There should be continuity. If
OK, go to Step 6. If not OK, repair the open ground
circuit to ground as required.
(6)
Reconnect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
15-way door wire harness connector for the DDM. If
OK, replace the faulty DDM. If not OK, repair the open
fused B(+) circuit to the fuse in the PDC as required.
ONE MIRROR INOPERATIVE
(1) If the one inoperative mirror is on the passen-
ger side, go to Step 2. If the one inoperative mirror is
on the driver side, go to Step 3.
(2)
Check if the passenger front door will lock and
unlock using the power lock switch on the driver side
front door. If OK, go to Step 3. If not OK, go to Step 6.
(3) Disconnect and isolate the battery negative
cable. Remove the trim panel from the front door.
Disconnect the 12-way mirror wire harness connector
from the door wire harness connector.
(4) Using two jumper wires, test the mirror as
shown in the Mirror Test chart (Fig. 2). If the mirror
tests OK, go to Step 5. If the mirror does not test
OK, replace the faulty mirror.(5) Disconnect the 12-way door wire harness con-
nector from the door module connector receptacle.
Check all of the circuits of the door wire harness
between the connector for the mirror and the connec-
tor for the door module for opens or shorts. If all of
the circuits are OK, replace the faulty door module.
If any of the circuits are not OK, repair the open or
shorted circuit(s) as required.
(6) Use a DRB scan tool and the proper Diagnostic
Procedures manual to test and repair the faulty Pro-
grammable Communications Interface (PCI) data bus
communication between the two door modules.
NO MIRROR HEAT
If one or both mirror heaters are inoperative,
(Refer to 8 - ELECTRICAL/HEATED MIRRORS -
DESCRIPTION).
(1) Disconnect and isolate the battery negative
cable. Remove the front door trim panel on the side
of the inoperative mirror heater.
(2) Disconnect the 12-way door wire harness con-
nector from the door module connector receptacle.
Check for continuity between the heater switched
ground circuit cavity and the heater 12V supply cir-
cuit cavity of the 12-way door wire harness connector
Fig. 2 Mirror Test
POWER MIRROR TEST TABLE
APPLY 12
VOLTS TO:APPLY
GROUND TO:MIRROR
REACTION
DRIVER SIDE
1 7 LEFT
7 1 RIGHT
87UP
7 8 DOWN
PASSENGER SIDE
1 7 LEFT
7 1 RIGHT
87UP
7 8 DOWN
8N - 16 POWER MIRRORSWJ
SIDEVIEW MIRROR (Continued)

POWER WINDOWS
TABLE OF CONTENTS
page page
POWER WINDOWS
DESCRIPTION.........................33
OPERATION...........................34
DIAGNOSIS AND TESTING - POWER
WINDOWS...........................34
POWER WINDOW SWITCH
DESCRIPTION.........................36
OPERATION...........................36
DIAGNOSIS AND TESTING - POWER
WINDOW SWITCH.....................37REMOVAL.............................37
INSTALLATION.........................38
WINDOW MOTOR
DESCRIPTION.........................38
OPERATION...........................38
DIAGNOSIS AND TESTING - WINDOW
MOTOR .............................38
REMOVAL.............................39
INSTALLATION.........................39
POWER WINDOWS
DESCRIPTION
Power operated driver side and passenger side
front and rear door windows are standard factory-in-
stalled equipment on this model. The power window
system allows each of the door windows to be raised
or lowered electrically by operating a switch on the
trim panel for that door. Additionally, the master
switches on the driver side front door trim panel
allow all of the windows to be operated from the
driver seat position. A power window lockout switch
on the driver side front door trim panel will allow the
driver to disable all of the passenger door window
switches.
The power window system functionally operates
when the ignition switch is in the On position. How-
ever, a unique feature of this system will allow the
power windows to be operated for up to forty-five sec-
onds after the ignition switch is turned to the Off
position, or until a front door is opened, whichever
occurs first.
An auto-down feature allows the driver side front
door window to be lowered all the way, even if the
window switch is released. The driver side front door
window switch must be depressed in the down direc-
tion to a second detent to begin an auto-down event.
Depressing the switch again in any direction cancel
the auto-down event and begin movement in the
direction specified.
This group covers the following components of the
power window system:
²Power window switches
²Power window motors.
Certain functions and features of the power win-
dow system rely upon resources shared with other
electronic modules in the vehicle over the Program-mable Communications Interface (PCI) data bus net-
work. The PCI data bus network allows the sharing
of sensor information. This helps to reduce wire har-
ness complexity, internal controller hardware, and
component sensor current loads. At the same time,
this system provides increased reliability, enhanced
diagnostics, and allows the addition of many new fea-
ture capabilities. For diagnosis of these electronic
modules or of the PCI data bus network, the use of a
DRB scan tool and the proper Diagnostic Procedures
manual are recommended.
The other electronic modules that may affect power
window system operation are as follows:
²Body Control Module (BCM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/BODY CONTROL/CENTRAL TIMER MODUL
- DESCRIPTION) for more information.
²Driver Door Module (DDM)-(Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DRIVER DOOR MODULE - DESCRIPTION)
for more information.
²Passenger Door Module (PDM)- (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/DRIVER DOOR MODULE - DESCRIPTION)
for more information.
This group covers diagnosis and service of only the
electrical components in the power window system.
For service of mechanical components, such as the
regulator, lift plate, window tracks, or glass refer to
Body. 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. Follow-
ing are general descriptions of the major components
in the power window system.
WJPOWER WINDOWS 8N - 33

OPERATION
The power window system includes the Driver
Door Module (DDM) and Passenger Door Module
(PDM), which are mounted in their respective front
door, the rear door power window switches mounted
on the rear doors, and the power window motors
mounted to the window regulator in each door. The
DDM houses four master power window switches, the
power window lockout switch and the control logic for
the driver side front and rear door power windows.
The PDM houses the passenger side front door power
window switch and the control logic for the passenger
side front and rear door power windows.
When a master power window switch on the DDM
is used to operate a passenger side power window,
the DDM sends the window switch actuation mes-
sage to the PDM over the Programmable Communi-
cations Interface (PCI) data bus. The PDM responds
to these messages by sending control outputs to move
the passenger side power window motors. In addi-
tion, when the power window lockout switch in the
DDM is actuated to disable power window operation,
a lockout message is sent to the PDM over the PCI
data bus.
The Body Control Module (BCM) also supports and
controls certain features of the power window sys-
tem. The BCM receives a hard wired input from the
ignition switch. The programming in the BCM allows
it to process the information from this input and
send ignition switch status messages to the DDM
and the PDM over the PCI data bus. The DDM and
PDM use this information and hard wired inputs
from the front door ajar switches to control the light-
ing of the power window switch lamps, and to control
the operation of the power window after ignition-off
feature.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power window system.
DIAGNOSIS AND TESTING - POWER
WINDOWS
Following are tests that will help to diagnose the
hard wired components and circuits of the power
window system. However, these tests may not prove
conclusive in the diagnosis of this system. In order to
obtain conclusive testing of the power window 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 power window system components must be
checked.The most reliable, efficient, and accurate means to
diagnose the power window system requires the use
of a DRB scan tool and the proper Diagnostic Proce-
dures manual. The DRB scan tool can provide confir-
mation 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 window motors are being sent the proper
hard wired outputs by the door modules for them to
perform their power window system functions.
For complete circuit diagrams, refer to the appro-
priate 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 connec-
tors, splices and grounds.
ALL WINDOWS INOPERATIVE
(1) Check the operation of the power lock switch
on the driver side front door. If all of the doors lock
and unlock, but none of the power windows operate,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to check the Body Control Module
(BCM), the Driver Door Module (DDM) and the PCI
data bus for proper operation. If not OK, go to Step
2.
(2) Check the operation of the power lock switch
on the passenger side front door. If the passenger
doors lock and unlock, but the driver side front door
does not, go to Step 5. If all of the power locks and
power windows are inoperative from both front doors,
go to Step 3.
(3) Check the fused B(+) fuse in the Power Distri-
bution Center (PDC). If OK, go to Step 4. If not OK,
repair the shorted circuit or component as required
and replace the faulty fuse.
(4) Check for battery voltage at the fused B(+) fuse
in the PDC. If OK, go to Step 5. If not OK, repair the
open fused B(+) circuit to the battery as required.
(5) Disconnect and isolate the battery negative
cable. Remove the trim panel from the driver side
front door. Disconnect the 15-way door wire harness
connector from the DDM connector receptacle. Check
for continuity between the ground circuit cavity of
the 15-way door wire harness connector for the DDM
and a good ground. There should be continuity. If
OK, go to Step 6. If not OK, repair the open ground
circuit to ground as required.
(6) Reconnect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
15-way door wire harness connector for the DDM. If
OK, replace the faulty DDM. If not OK, repair the
open fused B(+) circuit to the fuse in the PDC as
required.
8N - 34 POWER WINDOWSWJ
POWER WINDOWS (Continued)

PASSENGER SIDE FRONT AND REAR WINDOWS
INOPERATIVE
If the driver side front and rear power windows
operate, but the passenger side front and rear do not,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to check the PCI data bus for proper
operation.
ONE WINDOW INOPERATIVE
The window glass and regulator mechanism must
be free to slide up and down for the power window
motor to function properly. If the window glass and
regulator is not free to move up and down, the motor
will overload and trip the integral circuit breaker. To
determine if the window glass and regulator are free,
disconnect the regulator plate from the glass. Then
slide the window up and down by hand.
There is an alternate method to check if the win-
dow glass and regulator mechanism is free. Position
the glass between the up and down stops. Then,
shake the glass in the door. Check that the glass can
be moved slightly from side to side, front to rear, and
up and down. Then check that the glass is not bound
tight in the tracks.
If the window glass and regulator mechanism is
free, refer toDoor Modulein Electrical, Power Win-
dows. If the glass is not free, inspect the window
glass mounting and operating hardware for damage
or improperly installed components. Refer toBodyto
check for proper installation or damage of the win-
dow glass mounting and operating hardware.
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 component requires the use of a DRB scan tool
and the proper Diagnostic Procedures manual.
If the problem being diagnosed is a rear door win-
dow that does not operate from the rear door switch,
but does operate from the master switch on the
driver side front door, (Refer to 8 - ELECTRICAL/
POWER WINDOWS/POWER WINDOW SWITCH -
DIAGNOSIS AND TESTING). If the problem is a
passenger side front or rear window that operates
from the switch on that door, but does not operate
from the master switch on the driver side front door,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to diagnose the circuitry of both door
modules and the PCI data bus. For complete circuit
diagrams, refer to the appropriate wiring informa-
tion. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
details of wire harness routing and retention, connec-tor pin-out information and location views for the
various wire harness connectors, splices and grounds.
(1) Disconnect and isolate the battery negative
cable. Remove the trim panel from the front door, but
do not disconnect the door wire harness connectors
from the door module. 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, properly connect the 15-way door
wire harness connector for the door module to the
door module connector receptacle.
(3) Disconnect the 15-way door wire harness con-
nector from the door module connector receptacle.
Check for continuity between the ground circuit cav-
ity of the 15-way door wire harness connector for the
door module and a good ground. There should be con-
tinuity. 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 fuse in the Power Dis-
tribution Center (PDC) as required.
(5) If the inoperative window is on a front door, go
to Step 6. If the inoperative window is on a rear door
go to Step 9.
(6) Disconnect and isolate the battery negative
cable. Disconnect the door wire harness connector
from the inoperative power window motor wire har-
ness connector. Check for continuity between the
front window driver up circuit cavity of the 15-way
door wire harness connector for the door module and
a good ground. Repeat the check for the front window
driver down circuit. In each case there should be no
continuity. If OK, go to Step 7. If not OK, repair the
shorted front window driver up or down circuit as
required.
(7) Check for continuity between the front window
driver up circuit cavities of the 15-way door wire har-
ness connector for the door module and the door wire
harness connector for the power window motor.
Repeat the check for the front window driver down
circuit. In each case there should be continuity. If
OK, go to Step 8. If not OK, repair the open front
window driver up or down circuit as required.
(8) Reconnect the 15-way door wire harness con-
nector back into the door module connector recepta-
cle. Connect the battery negative cable. Connect the
probes of a reversible DC digital voltmeter to the
door wire harness connector for the power window
motor. Observe the voltmeter while actuating the
switch for that window in the up and down direc-
tions. There should be battery voltage for as long as
the switch is held in both the up and down positions,
WJPOWER WINDOWS 8N - 35
POWER WINDOWS (Continued)

event will be automatically cancelled and the window
movement will be stopped if the DDM circuitry
detects a second input from the driver side front door
power window switch, in either direction.
Each power window switch, except the lockout
switch, is illuminated by a Light-Emitting Diode
(LED) when the ignition switch is turned to the On
position. However, when the lockout switch is placed
in the Lock position, the LED for the locked-out front
and rear passenger door power window switches is
turned off.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power window switches.
DIAGNOSIS AND TESTING - POWER WINDOW
SWITCH
The diagnosis found here applies only to the rear
door power window switches. If the problem being
diagnosed is an inoperative power window switch
illumination lamp, but the power window switch
operates as designed, replace the faulty rear door
power window switch(verify the power lockout
switch is not actuated). For complete circuit dia-
grams, 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 and isolate the battery negative
cable.
(2) Remove the power window switch from the
rear door trim panel. (Refer to 8 - ELECTRICAL/
POWER WINDOWS/POWER WINDOW SWITCH -
REMOVAL).
(3) Check the rear door power window switch con-
tinuity as shown in the Rear Door Power Window
Switch Continuity chart (Fig. 1). If OK, (Refer to 8 -
ELECTRICAL/POWER WINDOWS/WINDOW
MOTOR - DIAGNOSIS AND TESTING). If not OK,
replace the faulty rear door power window switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the trim panel from the rear door.
(Refer to 23 - BODY/DOORS - REAR/TRIM PANEL -
REMOVAL) for the procedures.
(3) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the sides of the switch
receptacle on the back of the rear door trim panel
away from the perimeter of the power window switch
to release the switch from the receptacle (Fig. 2).
(4) Remove the power window switch from the
rear door trim panel switch receptacle.
Fig. 1 Rear Door Power Window Switch Continuity
SWITCH POSITION CONTINUITY BETWEEN
LED 3 AND 6
OFF 1 AND 2
OFF 4 AND 5
FORWARD 1 AND 2
FORWARD 5 AND 6
REARWARD 2 AND 6
REARWARD 4 AND 5
Fig. 2 Rear Door Power Window Switch Remove/
Install
1 - REAR DOOR TRIM PANEL
2 - TRIM PANEL RECEPTACLE
3 - POWER WINDOW SWITCH
WJPOWER WINDOWS 8N - 37
POWER WINDOW SWITCH (Continued)

INSTALLATION
(1) Position the power window switch to the rear
door trim panel switch receptacle.
(2) Press firmly and evenly on the back of the
power window switch until it snaps into rear door
trim panel switch receptacle.
(3) Install the trim panel onto the rear door. (Refer
to 23 - BODY/DOORS - REAR/TRIM PANEL -
INSTALLATION) for the procedures.
(4) Reconnect the battery negative cable.
WINDOW MOTOR
DESCRIPTION
Power operated front and rear door windows are
standard equipment on this model. Each door has a
permanent magnet reversible electric motor with an
integral right angle gearbox mechanism that oper-
ates the window regulator. In addition, each power
window motor is equipped with an integral self-reset-
ting circuit breaker to protect the motor from over-
loads.
The power window motor gearbox housing is
secured to the window regulator drum housing with
screws. The window regulators used in all four doors
are single vertical post cable-and-drum type. A
molded plastic slider guided by the post is driven by
the regulator cables. The slider raises and lowers the
window glass through a steel lift plate attachment.
Front and rear glass channels within each door guide
and stabilize each end of the glass.
The power window motor and gearbox assembly
cannot be repaired and, if faulty or damaged, the
entire power window motor and gearbox unit must be
replaced. The window regulators are available for
service. (Refer to 23 - BODY/DOOR - FRONT/WIN-
DOW REGULATOR - REMOVAL) or (Refer to 23 -
BODY/DOORS - REAR/WINDOW REGULATOR -
REMOVAL) for the regulator service procedures.
OPERATION
A positive and negative battery connection to the
two motor terminals will cause the power window
motor to rotate in one direction. Reversing the cur-
rent through these same two connections will cause
the motor to rotate in the opposite direction.
When the power window motor operates, it rotates
the regulator cable drum through its gearbox. The
window regulator cable drum is connected through
two cables to the plastic slider on the vertical post.
As the cable drum rotates, it lets cable out on one
side of the drum, and takes cable in on the other side
of the drum. The changes in cable length move the
slider up or down the vertical post, raising or lower-
ing the window glass.If the window regulator or window glass bind,
encounter obstructions, or reach their travel limits it
overloads the power window motor. The overloading
condition causes the power window motor self-reset-
ting circuit breaker to open, which stops the motor
from running.
DIAGNOSIS AND TESTING - WINDOW MOTOR
Before you proceed with this diagnosis, confirm
proper switch operation. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/DRIVER
DOOR MODULE - OPERATION) or (Refer to 8 -
ELECTRICAL/POWER WINDOWS/POWER WIN-
DOW SWITCH - OPERATION). For complete circuit
diagrams, refer to the appropriate wiring informa-
tion. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
details of wire harness routing and retention, connec-
tor pin-out information and location views for the
various wire harness connectors, splices and grounds.
(1) Remove the trim panel from the door with the
inoperative power window. (Refer to 23 - BODY/
DOOR - FRONT/TRIM PANEL - REMOVAL) or
(Refer to 23 - BODY/DOORS - REAR/TRIM PANEL -
REMOVAL) for the procedures.
(2) Disconnect the door wire harness connector
from the power window motor wire harness connec-
tor. Apply battery current to one cavity of the power
window motor wire harness connector, and apply
ground to the other cavity of the connector. The
power window motor should operate in one direction.
Remember, if the window is in the full up or full
down position, the motor will not operate in that
direction by design. If OK, go to Step 3. If not OK,
replace the faulty power window motor.
(3) Reverse the battery and ground connections to
the two cavities of the power window motor wire har-
ness connector. The power window motor should now
operate in the other direction. Remember, if the win-
dow is in the full up or full down position, the motor
will not operate in that direction by design. If OK, go
to Step 4. If not OK, replace the faulty power window
motor.
(4) If the power window motor operates in both
directions, check the operation of the window glass
and regulator mechanism through its complete up
and down travel. There should be no binding or stick-
ing of the window glass or regulator mechanism
through the entire travel range. If not OK, (Refer to
23 - BODY/DOOR - FRONT/WINDOW REGULATOR
- REMOVAL) or (Refer to 23 - BODY/DOORS -
REAR/WINDOW REGULATOR - REMOVAL) to
check for proper installation or damage of the win-
dow glass mounting and operating hardware.
8N - 38 POWER WINDOWSWJ
POWER WINDOW SWITCH (Continued)

²Passenger Airbag- The passenger airbag is
located on the instrument panel, beneath the instru-
ment panel top pad and above the glove box on the
passenger side of the vehicle.
²Passenger Knee Blocker- The passenger knee
blocker is a structural reinforcement that is integral
to and concealed within the glove box door.
²Side Impact Sensor- Two side impact sensors
are used on vehicles with the optional side curtain
airbags, one left side and one right side. One sensor
is located behind the B-pillar trim near the base of
each B-pillar.
²Side Curtain Airbag- In vehicles equipped
with this option, a side curtain airbag is located on
each inside roof side rail above the headliner, and
extends from the A-pillar to just beyond the C-pillar.
The ACM and the EMIC each contain a central
processing unit and programming that allow them to
communicate with each other using the Programma-
ble Communication Interface (PCI) data bus network.
This method of communication is used by the ACM
for control of the airbag indicator on all models
equipped with dual front airbags. (Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
COMMUNICATION - DESCRIPTION).
Hard wired circuitry connects the supplemental
restraint system components to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to several wire harnesses, which
are routed throughout the vehicle and retained by
many different methods. These circuits may be con-
nected to each other, to the vehicle electrical system,
and to the supplemental restraint system compo-
nents through the use of a combination of soldered
splices, splice block connectors, and many different
types of wire harness terminal connectors and insu-
lators. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures, further
details on wire harness routing and retention, as well
as pin-out and location views for the various wire
harness connectors, splices and grounds.
OPERATION
ACTIVE RESTRAINTS
The primary passenger restraints in this or any
other vehicle are the standard equipment factory-in-
stalled seat belts. Seat belts are referred to as an
active restraint because the vehicle occupants are
required to physically fasten and properly adjust
these restraints in order to benefit from them. See
the owner's manual in the vehicle glove box for more
information on the features, use and operation of all
of the factory-installed active restraints.PASSIVE RESTRAINTS
The passive restraints system is referred to as a
supplemental restraint system because they were
designed and are intended to enhance the protection
for the vehicle occupants of the vehicleonlywhen
used in conjunction with the seat belts. They are
referred to as passive systems because the vehicle
occupants are not required to do anything to make
them operate; however, the vehicle occupants must
be wearing their seat belts in order to obtain the
maximum safety benefit from the factory-installed
supplemental restraint systems.
The supplemental restraint system electrical cir-
cuits are continuously monitored and controlled by a
microprocessor and software contained within the
Airbag Control Module (ACM). An airbag indicator in
the ElectroMechanical Instrument Cluster (EMIC)
illuminates for about seven seconds as a bulb test
each time the ignition switch is turned to the On or
Start positions. Following the bulb test, the airbag
indicator is turned on or off by the ACM to indicate
the status of the supplemental restraint system. If
the airbag indicator comes on at any time other than
during the bulb test, it indicates that there is a prob-
lem in the supplemental restraint system electrical
circuits. Such a problem may cause airbags not to
deploy when required, or to deploy when not
required.
Deployment of the supplemental restraints
depends upon the angle and severity of an impact.
Deployment is not based upon vehicle speed; rather,
deployment is based upon the rate of deceleration as
measured by the forces of gravity (G force) upon the
impact sensors. When an impact is severe enough,
the microprocessor in the ACM signals the inflator
unit of the airbag module to deploy the airbag. Dur-
ing a frontal vehicle impact, the knee blockers work
in concert with properly fastened and adjusted seat
belts to restrain both the driver and the front seat
passenger in the proper position for an airbag deploy-
ment. The knee blockers also absorb and distribute
the crash energy from the driver and the front seat
passenger to the structure of the instrument panel.
Typically, the vehicle occupants recall more about
the events preceding and following a collision than
they have of an airbag deployment itself. This is
because the airbag deployment and deflation occur so
rapidly. In a typical 48 kilometer-per-hour (30 mile-
per-hour) barrier impact, from the moment of impact
until the airbags are fully inflated takes about 40
milliseconds. Within one to two seconds from the
moment of impact, the airbags are almost entirely
deflated. The times cited for these events are approx-
imations, which apply only to a barrier impact at the
given speed. Actual times will vary somewhat,
8O - 4 RESTRAINTSWJ
RESTRAINTS (Continued)

(8) Connect negative battery cable at battery.
(9) Before starting engine, operate accelerator
pedal to check for any binding.
SERVO
DESCRIPTION
The servo unit consists of a solenoid valve body,
and a vacuum chamber. The solenoid valve body con-
tains three solenoids:
²Vacuum
²Vent
²Dump
The vacuum chamber contains a diaphragm with a
cable attached to control the throttle linkage.
OPERATION
The Powertrain Control Module (PCM) controls the
solenoid valve body. The solenoid valve body controls
the application and release of vacuum to the dia-
phragm of the vacuum servo. The servo unit cannot
be repaired and is serviced only as a complete assem-
bly.
Power is supplied to the servo's by the PCM
through the brake switch. The PCM controls the
ground path for the vacuum and vent solenoids.The dump solenoid is energized anytime it receives
power. If power to the dump solenoid is interrupted,
the solenoid dumps vacuum in the servo. This pro-
vides a safety backup to the vent and vacuum sole-
noids.
The vacuum and vent solenoids must be grounded
at the PCM to operate. When the PCM grounds the
vacuum servo solenoid, the solenoid allows vacuum
to enter the servo and pull open the throttle plate
using the cable. When the PCM breaks the ground,
the solenoid closes and no more vacuum is allowed to
enter the servo. The PCM also operates the vent sole-
noid via ground. The vent solenoid opens and closes a
passage to bleed or hold vacuum in the servo as
required.
The PCM duty cycles the vacuum and vent sole-
noids to maintain the set speed, or to accelerate and
decelerate the vehicle. To increase throttle opening,
the PCM grounds the vacuum and vent solenoids. To
decrease throttle opening, the PCM removes the
grounds from the vacuum and vent solenoids. When
the brake is released, if vehicle speed exceeds 30
mph to resume, 35 mph to set, and the RES/ACCEL
switch has been depressed, ground for the vent and
vacuum circuits is restored.
REMOVAL
The speed control servo is attached to a bracket.
The bracket and servo assembly are located below
the battery tray.
(1) Disconnect negative battery cable at battery.
(2) Disconnect positive battery cable at battery.
(3) Remove air cleaner housing at top of throttle
body and disconnect servo cable at throttle body.
Refer to Servo Cable Removal/Installation.
(4) Remove battery from battery tray.
(5) Disconnect wiring at battery tray.
(6) Disconnect positive battery cable at Power Dis-
tribution Center (PDC).
(7) Loosen PDC at battery tray.
(8) Remove 4 battery tray bolts. One of these bolts
attaches to speed control bracket flange that sup-
ports battery tray. While removing battery tray, dis-
connect battery temperature sensor electrical
connector at sensor.
(9) Disconnect vacuum line at servo vacuum hose
fitting (Fig. 5) .
(10) Disconnect electrical connector at servo (Fig.
5) .
If servo and mounting bracket are being removed
as one assembly, remove two mounting nuts (Fig. 5) .
These are located above right-front tire. Remove
inner fender clips and pry inner fender back slightly
to gain access to mounting nuts.
Fig. 4 Speed Control Cable at BracketÐ4.7L V-8
Engine
1 - PLASTIC CABLE MOUNT
2 - SPEED CONTROL CABLE
3 - BRACKET
4 - SLIDE FOR REMOVAL
WJSPEED CONTROL 8P - 5
CABLE (Continued)