2002 JEEP LIBERTY front pinion

traction. Pulling power is provided continuously until
both wheels loose traction. If both wheels slip due to
unequal traction, Trac-lokŸ operation is normal. In
extreme cases of differences of traction, the wheel
with the least traction may spin.
DIAGNOSIS AND TESTING - AXLE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, incorrect pinion depth, tooth
contact, worn/damaged gears, or the carrier housing
not having the proper offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
cle turns. A worn pinion shaft can also cause a snap-
ping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-
tial bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changeswhen the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side±gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft.
²Missing drive shaft balance weight(s).
²Worn or out-of-balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rearend vibra-
tion. Do not overlook engine accessories, brackets
and drive belts.
NOTE: All driveline components should be exam-
ined before starting any repair.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed.
²Transmission shift operation.
²Loose engine/transmission/transfer case mounts.
²Worn U-joints.
²Loose spring mounts.
²Loose pinion gear nut and yoke.
²Excessive ring gear backlash.
²Excessive side gear to case clearance.
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
3 - 88 REAR AXLE-81/4KJ
REAR AXLE - 8 1/4 (Continued)

PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
24232221 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 020.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 020.00120.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 020.00120.00220.003
0+0.004 +0.003 +0.002 +0.001 020.00120.00220.00320.004
21+0.003 +0.002 +0.001 020.00120.00220.00320.00420.005
22+0.002 +0.001 020.00120.00220.00320.00420.00520.006
23+0.001 020.00120.00220.00320.00420.00520.00620.007
24020.00120.00220.00320.00420.00520.00620.00720.008
PINION DEPTH MEASUREMENT
Measurements are taken with pinion bearing cups and
pinion bearings installed in the housing. Take measure-
ments with Pinion Gauge Set and Dial Indicator C-3339.
(1) Assemble Pinion Height Block 6739, Pinion
Block 8540 and rear pinion bearing onto Screw 6741
(Fig. 10).(2) Insert assembled height gauge components,
rear bearing, and screw into the housing through
pinion bearing cups (Fig. 11).
(3) Install front pinion bearing and Cone-Nut 6740
hand tight (Fig. 10).
(4) Place Arbor Disc 8541 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 12).
Install differential bearing caps on Arbor Discs and
tighten cap bolts to 41 N´m (30 ft. lbs.).
NOTE: Arbor Discs 8541 has different step diame-
ters to fit other axles. Choose proper step for axle
being serviced.
(5) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.
Fig. 10 Pinion Depth Gauge Tools
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOOK
8 - ARBOR DISC
Fig. 11 Pinion Height Block
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
KJREAR AXLE - 8 1/4 3 - 93
REAR AXLE - 8 1/4 (Continued)

(10) Remove pinion shaft seal with a pry tool or
slide-hammer mounted screw.
(11) Remove oil slinger, if equipped, and front pin-
ion bearing.
(12) Remove front pinion bearing cup with
Remover C-4345 and Handle C-4171 (Fig. 50).
(13) Remove rear bearing cup from housing (Fig.
51) with Remover C-4307 and Handle C-4171.
(14) Remove collapsible preload spacer (Fig. 52).
(15) Remove rear bearing from the pinion (Fig. 53)
with Puller/Press C-293-PA and Adapters C-293-47.
(16) Remove depth shims from the pinion shaft
and record the shims thickness.
INSTALLATION
NOTE: A pinion depth shim/oil baffle is placed
between the rear pinion bearing cone and pinion
gear. If the ring and pinion gears are reused, the
original pinion depth shim/oil baffle can be used.
Refer to Adjustments (Pinion Gear Depth) to select
the proper shim thickness if ring and pinion gear
are replaced.
(1) Apply Mopar Door Ease or equivalent lubricant
to outside surface of pinion bearing cups.
(2) Install rear pinion bearing cup (Fig. 54) with
Installer C-4308 and Handle C-4171 and verify cup is
seated.(3) Install front pinion bearing cup (Fig. 55) with
Installer D-130 and Handle C-4171 and verify cup is
seated.
Fig. 50 Front Pinion Bearing Cup
1 - REMOVER
2 - HANDLE
Fig. 51 Rear Pinion Bearing Cup
1 - DRIVER
2 - HANDLE
Fig. 52 Collapsible Spacer
1 - COLLAPSIBLE SPACER
2 - SHOULDER
3 - PINION
4 - PINION DEPTH SHIM
5 - REAR BEARING
3 - 112 REAR AXLE-81/4KJ
PINION GEAR/RING GEAR/TONE RING (Continued)

(4) Install pinion front bearing and oil slinger, if
equipped.(5) Apply a light coating of gear lubricant on the
lip of pinion seal and install seal with Installer
C-4076-B and Handle C-4735 (Fig. 56).
(6) Place proper thickness depth shim on the pin-
ion.
(7) Install rear bearing and slinger if equipped, on
the pinion shaft (Fig. 57) with Installer 6448 and a
press.
(8) Install anewcollapsible preload spacer on pin-
ion shaft and install pinion in housing (Fig. 58).
(9) Install pinion in housing.
(10) Install yoke with Installer C-3718 and Yoke
Holder 6719A.
Fig. 53 Rear Pinion Bearing Puller
1 - PULLER
2 - VISE
3 - ADAPTERS
4 - PINION GEAR SHAFT
Fig. 54 Rear Pinion Bearing Cup
1 - INSTALLER
2 - HANDLE
Fig. 55 Front Bearing Cup
1 - INSTALLER
2 - HANDLE
Fig. 56 Pinion Seal
1 - HANDLE
2 - DIFFERENTIAL HOUSING
3 - INSTALLER
KJREAR AXLE - 8 1/4 3 - 113
PINION GEAR/RING GEAR/TONE RING (Continued)

tion switch is in any position except On, and elec-
tronic messages are received over the PCI data bus
from the BCM indicating that the exterior lights are
On with the ignition switch in any position except
On, and the status of the driver side front door is not
closed. The BCM uses internal programming and
hard wired inputs from the left (lighting) control
stalk of the multi-function switch, the ignition
switch, and the driver side front door ajar switch to
determine the proper messages to send to the EMIC.
These chimes will continue to sound until the exte-
rior lighting is turned Off, until the ignition switch is
turned to the On position, or until the status of the
driver side front door ajar input changes from not
closed to closed, whichever occurs first.
²Key-In-Ignition Warning- The EMIC chime
tone generator will generate repetitive ªbong-likeº
chime tones at a fast rate when the ignition switch is
in any position except On, and electronic messages
are received over the PCI data bus from the BCM
indicating that the key is in the ignition lock cylinder
with the ignition switch in any position except On,
and the driver side front door is not closed. The BCM
internal programming and hard wired inputs from
the key-in ignition circuitry of the ignition switch,
the ignition switch, and the driver side front door
ajar switch to determine the proper messages to send
to the EMIC. These chimes will continue to sound
until the key is removed from the ignition lock cylin-
der, until the ignition switch is turned to the On
position, or until the status of the driver side front
door ajar input changes from not closed to closed,
whichever occurs first.
²Low Coolant Warning- On vehicles equipped
with a diesel engine, the EMIC chime tone generator
will generate a single ªbong-likeº chime tone when
the ignition switch is first turned to the On position
and a hard wired input from the engine coolant level
sensor to the EMIC indicates that the coolant level is
low for more than about one-quarter second. Any
time after the ignition switch is first turned to the
On position, the EMIC uses internal programming to
check the status of the engine coolant level sensor
inputs about once every second, then adjusts an
internal counter up or down based upon the status of
this input. When the counter accumulates thirty
inputs indicating that the coolant level is low, a sin-
gle chime tone is sounded. This strategy is intended
to reduce the effect that coolant sloshing within the
coolant reservoir can have on reliable chime warning
operation. This warning will only occur once during
an ignition cycle.
²Low Fuel Warning- Each time the ignition
switch is turned to the On position, the EMIC chime
tone generator will generate a single ªbong-likeº
chime tone the first time an electronic message isreceived over the PCI data bus from the PCM
requesting ªLow Fuelº indicator illumination. The
chime will only occur a second time during the same
ignition cycle if another electronic message has been
received from the PCM indicating that there is an
increase in the fuel level equal to about 3 liters (0.8
gallon), then a subsequent electronic message from
the PCM requests ªLow Fuelº indicator illumination.
This strategy combined with filtering performed by
the internal programming of the PCM on the fuel
tank sending unit input is intended to reduce the
possibility of fuel sloshing within the fuel tank caus-
ing multiple low fuel warning chimes during a given
ignition cycle. The EMIC will also respond with the
low fuel warning chime when electronic fuel level
messages are received from the PCM indicating that
the hard wired input to the PCM from the fuel tank
sending unit is an open circuit (greater than full), or
a short circuit (less than empty).
²Low Washer Fluid Warning- The EMIC
chime tone generator will generate a single ªbong-
likeº chime tone when the ignition switch is turned
to the On position and a hard wired input from the
washer fluid level switch to the EMIC indicates the
washer fluid is low for more than about one-quarter
second. Any time after the ignition switch is first
turned to the On position, the EMIC uses internal
programming to check the status of the washer fluid
level switch inputs about once every second, then
adjusts an internal counter up or down based upon
the status of this input. When the counter accumu-
lates thirty inputs indicating that the washer fluid
level is low, a single chime tone is sounded. This
strategy is intended to reduce the effect that fluid
sloshing within the washer reservoir can have on
reliable chime warning operation. This warning will
only occur once during an ignition cycle.
²Overspeed Warning- The EMIC chime tone
generator will generate repetitive ªbong-likeº chime
tones at a slow rate when the ignition switch is in
the On position, and an electronic message received
over the PCI data bus from the PCM indicates that
the vehicle speed is over a programmed speed value.
The PCM uses internal programming and distance
pulse information received over a hard wired vehicle
speed pulse input from the BCM to determine the
proper vehicle speed messages to send to the EMIC.
The BCM uses an internally programmed electronic
pinion factor and a hard wired input from the rear
wheel speed sensor to calculate the proper distance
pulse information to send to the PCM. The electronic
pinion factor represents the proper tire size and axle
ratio information for the vehicle. These chimes will
continue to sound until the vehicle speed messages
are below the programmed speed value, or until the
ignition switch is turned to the Off position, which-
8B - 4 CHIME/BUZZERKJ
CHIME WARNING SYSTEM (Continued)

²Fog Lamp Control- The premium BCM pro-
vides fog lamp control for front fog lamps (optional),
and rear fog lamps (in required markets only).
²Front Wiper System Status- The BCM moni-
tors the status of the front wiper motor park switch.
²Fuel Economy and Distance to Empty Cal-
culations- The BCM calculates and transmits the
fuel economy and Distance To Empty (DTE) data.
²Headlamp Time Delay- The BCM provides a
headlamp time delay feature with the ignition switch
in the Off position.
²Heated Rear Glass Control- The BCM pro-
vides control and timer functions for the heated rear
glass feature and transmits the system status.
²Ignition On/Off Timer- The BCM monitors
and transmits the elapsed ignition On timer data
and monitors the ignition Off time.
²Ignition Switch Position Status- The BCM
monitors and transmits the status of the ignition
switch.
²Instrument Panel Dimming- The BCM mon-
itors and transmits the selected illumination inten-
sity level of the panel lamps dimmer switch.
²Interior Lamp Load Shedding- The BCM
provides a battery saver feature which will automat-
ically turn off all interior lamps that remain on after
a timed interval.
²Interior Lighting Control- The BCM moni-
tors inputs from the interior lighting switch, the door
ajar switches, the flip-up glass ajar switch, the tail-
gate ajar switch, the cargo lamp switch, the reading
lamp switches, and the Remote Keyless Entry (RKE)
module to provide courtesy lamp control. This
includes support for timed illuminated entry with
theater-style fade-to-off and courtesy illumination
defeat features.
²Intermittent Wipe and Front Wiper System
Control- The BCM monitors inputs from the front
wiper and washer switch and the front wiper motor
park switch to provide front wiper system control
through the wiper on/off and high/low relays. This
includes support for adjustable intermittent wipe,
mist wipe (also known as pulse wipe), and wipe-after-
wash features.
²Key-In-Ignition Switch Status- The BCM
monitors and transmits the status of the key-in-igni-
tion switch.
²Panic Mode- The BCM provides support for
the Remote Keyless Entry (RKE) system panic mode
feature.
²Parade Mode- The BCM provides a parade
mode (also known as funeral mode) that allows the
interior Vacuum Fluorescent Displays (VFD) to be
illuminated at full intensity while driving in daylight
with the exterior lamps On.²Power Locks- The BCM monitors inputs from
the power lock switches and the Remote Keyless
Entry (RKE) module (optional) to provide control of
the power lock motors through outputs to the lock,
unlock, and driver unlock (RKE only) relays. This
includes support for rolling door locks (also known as
automatic door locks) and a door lock inhibit mode.
²Programmable Features- The BCM provides
support for several standard and optional program-
mable features, including: rolling door locks, head-
lamp time delay interval, Remote Keyless Entry
(RKE) driver-door-only or unlock-all-doors, RKE opti-
cal chirp, and RKE audible chirp.
²Remote Keyless Entry- The premium BCM
provides the optional Remote Keyless Entry (RKE)
system features, including support for the RKE Lock,
Unlock (with optional driver-door-only unlock, and
unlock-all-doors), rear flip-up glass control, Panic,
audible chirp, optical chirp, and illuminated entry
modes, as well as the ability to be programmed to
recognize up to four RKE transmitters.
²Rolling Door Locks- The BCM provides sup-
port for the power lock system rolling door locks fea-
ture (also known as automatic door locks).
²Tailgate and Flip-Up Glass Ajar Status- The
BCM monitors and transmits the status of the tail-
gate and rear flip-up glass ajar switches.
²Remote Radio Switch Interface- The pre-
mium BCM monitors and transmits the status of the
optional remote radio switches.
²Self-Diagnostics- The BCM provides support
for diagnostics through communication with the
DRBIIItscan tool over the PCI data bus network.
Each analog and digital input can be verified, and
each output can be actuated through the use of this
diagnostic protocol. The BCM also stores Diagnostic
Trouble Codes (DTCs) to assist in troubleshooting
this unit.
²Vacuum Fluorescent Display Synchroniza-
tion- The BCM transmits panel lamp intensity data
which allows modules with Vacuum Fluorescent Dis-
plays (VFD) to coordinate their illumination inten-
sity.
²Vehicle Speed System- The BCM monitors a
vehicle speed input from the vehicle speed sensor
(without Antilock Brake System [ABS]) or from the
Controller Antilock Brake (CAB)(with ABS), calcu-
lates the vehicle speed based upon a programmed
axle ratio/tire size (electronic pinion factor), and
transmits the vehicle speed information to the Pow-
ertrain Control Module (PCM) on a hard wired out-
put circuit.
²Vehicle Theft Security System- The pre-
mium BCM monitors inputs from the door cylinder
lock switches, the tailgate cylinder lock switch, the
door ajar switches, the tailgate ajar switch, the
8E - 4 ELECTRONIC CONTROL MODULESKJ
BODY CONTROL MODULE (Continued)

²Vacuum Fluorescent Display Synchroniza-
tion (CMTC, EMIC, Radio)
²Vehicle Theft Security System Status (PCM,
ITM) - premium only
Refer to the appropriate diagnostic information for
additional details.
DIAGNOSIS AND TESTING - BODY CONTROL
MODULE
The hard wired inputs to and outputs from the
Body Control Module (BCM), as well as other hard
wired circuits for this module may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the
BCM, the Programmable Communications Interface
(PCI) data bus network, or the electronic messages
received and transmitted by the BCM over the PCI
data bus. The most reliable, efficient, and accurate
means to diagnose the BCM and the PCI data bus
network inputs to and outputs from this module
requires the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
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 har-
ness connectors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
NOTE: Before replacing a Body Control Module
(BCM), use a DRBIIITscan tool to retrieve the cur-
rent settings for the BCM programmable features
and the axle ratio/tire size (electronic pinion factor).
Refer to the appropriate diagnostic information.
These settings should be duplicated in the replace-
ment BCM using the DRBIIITscan tool before
returning the vehicle to service.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the Junction Block Module (JBM) from
the instrument panel end bracket on the driver side
of the vehicle. (Refer to 8 - ELECTRICAL/POWER
DISTRIBUTION/JUNCTION BLOCK - REMOVAL).
(3) Remove the four screws that secure the BCM
to the Junction Block (JB) (Fig. 3).
(4) Remove the BCM from the JB.
(5) If the vehicle is equipped with the optional
Remote Keyless Entry (RKE) system, remove the
RKE module from the receptacle on the BCM. (Refer
to 8 - ELECTRICAL/POWER LOCKS/REMOTE KEY-
LESS ENTRY MODULE - REMOVAL).
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER DIAGNOSIS OR SERVICE. THIS IS THE ONLY
SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
KJELECTRONIC CONTROL MODULES 8E - 7
BODY CONTROL MODULE (Continued)

in parallel with the IC where the two pigtail wire
leads connect to the IC pins.
The seat belt switch cannot be adjusted or repaired
and, if faulty or damaged, the entire seat belt buckle-
half unit must be replaced.
OPERATION
The seat belt switches are designed to provide a
status signal to the seat belt switch sense inputs of
the Airbag Control Module (ACM) indicating whether
the front seat belts are fastened. The ACM uses the
seat belt switch inputs as a factor in determining
what level of force with which it should deploy the
multistage driver and passenger airbags. In addition,
the ACM sends electronic messages to the ElectroMe-
chanical Instrument Cluster (EMIC) to control the
seat belt indicator based upon the status of the
driver side front seat belt switch. A spring-loaded
plastic slide with a small, enclosed permanent mag-
net is integral to the buckle latch mechanism. When
a seat belt tip-half is inserted and latched into the
seat belt buckle, the slide is pushed downward and
into close proximity of the Hall Effect Integrated Cir-
cuit (IC) chip within the buckle, which induces a cur-
rent within the chip. The chip provides this induced
current as an output to the ACM, which monitors the
current to determine the status of the front seat
belts. When the seat belt is unbuckled, the spring-
loaded slide and permanent magnet move upward
and away from the IC, causing the output current
from the seat belt switch to be reduced.
The seat belt switch receives a supply current from
the ACM, and the ACM senses the status of the front
seat belts through its pigtail wire connection to the
seat wire harness. The ACM also monitors the condi-
tion of the seat belt switch circuits through circuit
resistance created by the diagnostic resistor. The
ACM will illuminate the airbag indicator in the
EMIC and store a Diagnostic Trouble Code (DTC) for
any fault that is detected in either seat belt switch
circuit. For proper diagnosis of the seat belt switches,
a DRBIIItscan tool is required. Refer to the appro-
priate diagnostic information.
SEAT BELT TENSIONER
DESCRIPTION
A driver side seat belt tensioner supplements the
driver airbag system for all versions of this model
(Fig. 34). The seat belt tensioner is integral to the
driver side front seat belt and retractor unit, which is
secured to the B-pillar on the left side of the vehicle.
The retractor is concealed beneath the molded plastic
B-pillar trim. The seat belt tensioner consists prima-
rily of a molded plastic tensioner housing, a tubularmetal piston housing, a piston, a short rack gear, a
set of pinion gears, a pyrotechnically activated gas
generator, and a short pigtail wire. All of these com-
ponents are located on one side of the retractor spool
on the outside of the retractor housing. The seat belt
tensioner is controlled by the Airbag Control Module
(ACM) and is connected to the vehicle electrical sys-
tem through a dedicated take out of the body wire
harness by a keyed and latching molded plastic con-
nector insulator to ensure a secure connection.
The seat belt tensioner cannot be repaired and, if
faulty or damaged, the entire driver side front seat
belt and retractor unit must be replaced. The seat
belt tensioner is not intended for reuse and must be
replaced following a deployment. A locked retractor
that will not allow the seat belt webbing to be
retracted or extracted is a sure indication that the
seat belt tensioner has been deployed and requires
replacement. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/FRONT SEAT BELT & RETRACTOR -
REMOVAL).
OPERATION
The seat belt tensioner is deployed by a signal gen-
erated by the Airbag Control Module (ACM) through
the driver seat belt tensioner line 1 and line 2 (or
squib) circuits. When the ACM sends the proper elec-
trical signal to the tensioner, the electrical energy
generates enough heat to initiate a small pyrotechnic
gas generator. The gas generator is installed in one
end of the tubular metal piston housing, which con-
tains a piston and a small rack gear. As the gas
expands, it pushes the piston and the rack gear
Fig. 34 Seat Belt Tensioner
1 - RETRACTOR
2 - TENSIONER HOUSING
3 - PISTON HOUSING
4 - PIGTAIL WIRE
5 - GAS GENERATOR
8O - 36 RESTRAINTSKJ
SEAT BELT SWITCH (Continued)