1998 DODGE RAM 1500 airbag disable

PARK LAMP RELAY
DESCRIPTION
The park lamp relay is located in the Power Dis-
tribution Center (PDC) of the vehicle. The park lamp
relay is a conventional International Standards
Organization (ISO) micro relay (Fig. 17). Relays con-
forming to the ISO specifications have common phys-
ical dimensions, current capacities, terminal
patterns, and terminal functions.
The park lamp relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The park lamp relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the park lamps. The movable common feed
contact point is held against the fixed normally
closed contact point by spring pressure. When the
relay coil is energized, an electromagnetic field is
produced by the coil windings. This electromagnetic
field draws the movable relay contact point away
from the fixed normally closed contact point, and
holds it against the fixed normally open contact
point. When the relay coil is de-energized, spring
pressure returns the movable contact point back
against the fixed normally closed contact point. A
resistor is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and
electromagnetic interference that can be generated as
the electromagnetic field of the relay coil collapses.The park lamp relay terminals are connected to
the vehicle electrical system through a connector in
the Junction Block (JB). The inputs and outputs of
the headlamp low beam relay include:
²Common Feed Terminal- The common feed
terminal (30) is connected to the park lamps through
the park lamp relay output circuit and provides
ground to the park lamps when the relay is de-ener-
gized, and battery current to the park lamps when-
ever the relay is energized.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a park lamp relay
control circuit. The FCM controls park lamp opera-
tion by controlling a ground path through this cir-
cuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the PDC through a fused B(+) circuit.
²Normally Open Terminal- The normally open
terminal (87) receives battery current at all times
from a fuse in the Power Distribution Center (PDC)
through a fused B(+) circuit.
²Normally Closed Terminal- The normally
closed terminal (87A) is connected to ground at all
times.
The park lamp relay can be diagnosed using con-
ventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - PARK LAMP
RELAY
The park lamp relay (Fig. 18) is located in the
Power Distribution Center (PDC). Refer to the appro-
priate wiring information.
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.
(1) Remove the park lamp relay from the PDC.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
Fig. 17 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
8L - 20 LAMPS/LIGHTING - EXTERIORDR

no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   8 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, reinstall the relay and use a DRBIIIt
scan tool to perform further testing. Refer to the
appropriate diagnostic information.
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.
(1) Disconnect and isolate the battery negative
cable.(2) Remove the Power Distribution Center (PDC)
cover.
(3) Remove the park lamp relay by grasping it
firmly and pulling it straight out from the receptacle
in the PDC.
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.
(1) Position the park lamp relay to the proper
receptacle in the Power Distribution Center (PDC).
(2) Align the park lamp relay terminals with the
terminal cavities in the PDC.
(3) Press firmly and evenly on the top of the park
lamp relay until the terminals are fully seated in the
PDC.
(4) Install the PDC cover.
(5) Reconnect the battery negative cable.
PARK/TURN SIGNAL LAMP
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the headlamp unit.(Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/HEAD-
LAMP UNIT - REMOVAL).
(3) Remove the bulb socket from the headlamp
unit.
(4) Release the front park/turn signal bulb locking
tabs and remove the bulb from the socket (Fig. 19).
INSTALLATION
(1) Install the front park/turn signal bulb into the
bulb socket.
(2) Install the bulb socket into the headlamp unit.
(3) Install the headlamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/HEAD-
LAMP UNIT - INSTALLATION).
Fig. 18 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
DRLAMPS/LIGHTING - EXTERIOR 8L - 21
PARK LAMP RELAY (Continued)

Certain functions and features of the power lock
system rely upon resources shared with other elec-
tronic modules in the vehicle over the Programmable
Communications Interface (PCI) data bus network.
For proper diagnosis of these electronic modules or of
the PCI data bus network, the use of a DRB IIIt
scan tool and the appropriate diagnostic information
are required.
CENTRAL LOCKING/UNLOCKING
The instrument cluster will lock all doors when a
cylinder lock switch is activated in the ªlockº posi-
tion. When the instrument cluster receives an unlock
command from one of the cylinder lock switches, it
will unlock only that door. If the instrument cluster
receives a second command within a 5 second period,
it will unlock all the remaining doors. The illumi-
nated entry will activate during door unlock.
ENHANCED ACCIDENT RESPONSE
Upon detection of an airbag deployment by way of
the PCI bus, the instrument cluster will:
²Immediately disable the power door lock output.
²Unlock all doors by activating the door unlock
output for approximately 300 milliseconds.
²After actuating the door unlock output, allow
the door lock motors to be activated if the door lock
input has been inactive (not erratic) for 2 seconds
since the reception of the airbag deployment mes-
sage.
REMOTE KEYLESS ENTRY
A Radio Frequency (RF) type Remote Keyless
Entry (RKE) system is an available factory-installed
option on this model. The RKE system allows the use
of a remote battery-powered radio transmitter to sig-
nal the instrument cluster to actuate the power lock
system. The RKE receiver operates on non-switched
battery current through a fuse in the Integrated
Power Module (IPM), so that the system remains
operational, regardless of the ignition switch position.
The RKE transmitters are also equipped with a
Panic button. If the Panic button on the RKE trans-
mitter is depressed, the horn will sound and the
exterior lights will flash on the vehicle for about
three minutes, or until the Panic button is depressed
a second time. A vehicle speed of about 25.7 kilome-
ters-per-hour (15 miles-per-hour) will also cancel the
panic event.
The RKE system can also perform other functions
on this vehicle. If the vehicle is equipped with the
optional Vehicle Theft Security System (VTSS), the
RKE transmitter will arm the VTSS when the Lock
button is depressed, and disarm the VTSS when the
Unlock button is depressed.
The RKE system includes two transmitters when
the vehicle is shipped from the factory, but the system
can retain the vehicle access codes of up to a total of
four transmitters. The transmitter codes are retained
in the RKE module memory, even if the battery is dis-
connected. If an RKE transmitter is faulty or lost,
new transmitter vehicle access codes can be pro-
grammed into the system using a DRB IIItscan tool.
This vehicle also offers several customer program-
mable features, which allows the selection of several
optional electronic features to suit individual prefer-
ences. Customer programmable feature options
affecting the RKE system include:
²Remote Unlock Sequence- Allows the option
of having only the driver side front door unlock when
the RKE transmitter Unlock button is depressed the
first time. The remaining doors unlock when the but-
ton is depressed a second time within 5 seconds of
the first unlock press. Another option is having all
doors unlock upon the first depression of the RKE
transmitter Unlock button.
²Sound Horn on Lock- Allows the option of
having the horn sound a short chirp as an audible
verification that the RKE system received a valid
Lock request from the RKE transmitter, or having no
audible verification.
²Flash Lights with Lock and Unlock- Allows
the option of having the park lamps flash as an opti-
cal verification that the RKE system received a valid
Lock request or Unlock request from the RKE trans-
mitter, or having no optical verification.
²Programming Additional Transmitters-
Allows up to a total of four transmitter vehicle access
codes to be stored in the receiver memory.
Certain functions and features of the RKE system
rely upon resources shared with other electronic
modules in the vehicle over the Programmable Com-
munications Interface (PCI) data bus network. For
diagnosis of these electronic modules or of the PCI
data bus network, the use of a DRB IIItscan tool
and the appropriate diagnostic information are
required.
OPERATION
POWER LOCKS
The instrument cluster locks or unlocks the doors
when an actuation input signal from a door lock
switch or Remote Keyless Entry Module (RKE) is
received. The instrument cluster turns on the output
drivers and provides a voltage level to the door lock
motor for a specified time. All passenger doors can be
locked or unlocked using a mechanical button
mounted on the door trim panel. The front passenger
doors can be locked or unlocked by using the key cyl-
inder.
8N - 2 POWER LOCKSDR
POWER LOCKS (Continued)

Airbag Control Module (ACM). An airbag indicator in
the ElectroMechanical Instrument Cluster (EMIC)
illuminates for about six seconds as a bulb test each
time the ignition switch is turned to the On or Start
positions. Following the bulb test, the airbag indica-
tor 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 of
the appropriate airbag units to deploy their airbag
cushions. The outboard front seat belt tensioners are
provided with a deployment signal by the ACM in
conjunction with the driver and passenger front air-
bags. During a frontal vehicle impact, the knee block-
ers 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 deployment. 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. The seat belt tensioner removes
the slack from the outboard front seat belts to pro-
vide further assurance that the driver and front seat
passenger are properly positioned and restrained for
an airbag deployment.
Typically, the vehicle occupants recall more about
the events preceding and following a collision than
they do of an airbag deployment itself. This is
because the airbag deployment and deflation occur
very 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
approximations, which apply only to a barrier impact
at the given speed. Actual times will vary somewhat,
depending upon the vehicle speed, impact angle,
severity of the impact, and the type of collision.
When the ACM monitors a problem in any of the
supplemental restraint system circuits or compo-
nents, including the seat belt tensioners, it stores a
fault code or Diagnostic Trouble Code (DTC) in its
memory circuit and sends an electronic message to
the EMIC to turn on the airbag indicator. Propertesting of the supplemental restraint system compo-
nents, the Programmable Communications Interface
(PCI) data bus, the electronic message inputs to and
outputs from the EMIC or the ACM, as well as the
retrieval or erasure of a DTC from the ACM or EMIC
requires the use of a DRBIIItscan tool. Refer to the
appropriate diagnostic information.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of all of the factory-installed passive restraints.
WARNING
WARNINGS - RESTRAINT SYSTEM
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, DURING AND FOLLOWING ANY SEAT BELT
OR CHILD RESTRAINT ANCHOR SERVICE, CARE-
FULLY INSPECT ALL SEAT BELTS, BUCKLES,
MOUNTING HARDWARE, RETRACTORS, TETHER
STRAPS, AND ANCHORS FOR PROPER INSTALLA-
TION, OPERATION, OR DAMAGE. REPLACE ANY
BELT THAT IS CUT, FRAYED, OR TORN.
STRAIGHTEN ANY BELT THAT IS TWISTED.
TIGHTEN ANY LOOSE FASTENERS. REPLACE ANY
BELT THAT HAS A DAMAGED OR INOPERATIVE
BUCKLE OR RETRACTOR. REPLACE ANY BELT
THAT HAS A BENT OR DAMAGED LATCH PLATE
OR ANCHOR PLATE. REPLACE ANY CHILD
RESTRAINT ANCHOR OR THE UNIT TO WHICH THE
ANCHOR IS INTEGRAL THAT HAS BEEN BENT OR
DAMAGED. NEVER ATTEMPT TO REPAIR A SEAT
BELT OR CHILD RESTRAINT COMPONENT.
ALWAYS REPLACE DAMAGED OR FAULTY SEAT
BELT AND CHILD RESTRAINT COMPONENTS WITH
THE CORRECT, NEW AND UNUSED REPLACEMENT
PARTS LISTED IN THE DAIMLERCHRYSLER MOPAR
PARTS CATALOG.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
DRRESTRAINTS 8O - 5
RESTRAINTS (Continued)

WARNING: TO AVOID PERSONAL INJURY OR
DEATH ON VEHICLES EQUIPPED WITH AIRBAGS,
BEFORE PERFORMING ANY WELDING OPERA-
TIONS DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE AND DISCONNECT
ALL WIRE HARNESS CONNECTORS FROM THE
AIRBAG CONTROL MODULE (ACM). FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND OTHER POSSIBLE DAMAGE TO THE SUPPLE-
MENTAL RESTRAINT SYSTEM CIRCUITS AND COM-
PONENTS.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, DO NOT ATTEMPT TO DISMANTLE AN AIR-
BAG UNIT OR TAMPER WITH ITS INFLATOR. DO
NOT PUNCTURE, INCINERATE, OR BRING INTO
CONTACT WITH ELECTRICITY. DO NOT STORE AT
TEMPERATURES EXCEEDING 93É C (200É F). AN
AIRBAG INFLATOR UNIT MAY CONTAIN SODIUM
AZIDE AND POTASSIUM NITRATE. THESE MATERI-
ALS ARE POISONOUS AND EXTREMELY FLAMMA-
BLE. CONTACT WITH ACID, WATER, OR HEAVY
METALS MAY PRODUCE HARMFUL AND IRRITAT-
ING GASES (SODIUM HYDROXIDE IS FORMED IN
THE PRESENCE OF MOISTURE) OR COMBUSTIBLE
COMPOUNDS. AN AIRBAG INFLATOR UNIT MAY
ALSO CONTAIN A GAS CANISTER PRESSURIZED
TO OVER 2500 PSI.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, WHEN HANDLING A SEAT BELT TEN-
SIONER RETRACTOR, PROPER CARE SHOULD BE
EXERCISED TO KEEP FINGERS OUT FROM UNDER
THE RETRACTOR COVER AND AWAY FROM THE
SEAT BELT WEBBING WHERE IT EXITS FROM THE
RETRACTOR COVER.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, REPLACE ALL RESTRAINT SYSTEM COM-
PONENTS ONLY WITH PARTS SPECIFIED IN THE
DAIMLERCHRYSLER MOPAR PARTS CATALOG.
SUBSTITUTE PARTS MAY APPEAR INTERCHANGE-
ABLE, BUT INTERNAL DIFFERENCES MAY RESULT
IN INFERIOR OCCUPANT PROTECTION.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, THE FASTENERS, SCREWS, AND BOLTS
ORIGINALLY USED FOR THE RESTRAINT SYSTEM
COMPONENTS MUST NEVER BE REPLACED WITH
ANY SUBSTITUTES. THESE FASTENERS HAVE
SPECIAL COATINGS AND ARE SPECIFICALLY
DESIGNED FOR THE RESTRAINT SYSTEM. ANY
TIME A NEW FASTENER IS NEEDED, REPLACE ITWITH THE CORRECT FASTENERS PROVIDED IN
THE SERVICE PACKAGE OR SPECIFIED IN THE
DAIMLERCHRYSLER MOPAR PARTS CATALOG.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, WHEN A STEERING COLUMN HAS AN AIR-
BAG UNIT ATTACHED, NEVER PLACE THE COL-
UMN ON THE FLOOR OR ANY OTHER SURFACE
WITH THE STEERING WHEEL OR AIRBAG UNIT
FACE DOWN.
DIAGNOSIS AND TESTING - SUPPLEMENTAL
RESTRAINT SYSTEM
Proper diagnosis and testing of the supplemental
restraint system components, the Programmable
Communications Interface (PCI) data bus, the data
bus electronic message inputs to and outputs from
the ElectroMechanical Instrument Cluster (EMIC),
the Airbag Control Module (ACM), as well as the
retrieval or erasure of a Diagnostic Trouble Code
(DTC) from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
STANDARD PROCEDURE
STANDARD PROCEDURE - HANDLING
NON-DEPLOYED SUPPLEMENTAL RESTRAINTS
At no time should any source of electricity be per-
mitted near the inflator on the back of a non-de-
ployed airbag or seat belt tensioner. When carrying a
non-deployed airbag, the trim cover or airbag cushion
side of the unit should be pointed away from the
body to minimize injury in the event of an accidental
deployment. If the airbag unit is placed on a bench or
any other surface, the trim cover or airbag cushion
side of the unit should be face up to minimize move-
8O - 6 RESTRAINTSDR
RESTRAINTS (Continued)

CAUTION: Deployed front airbags having two initia-
tors (squibs) in the airbag inflator may or may not
have live pyrotechnic material within the inflator. Do
not dispose of these airbags unless you are sure of
complete deployment. Refer to AIRBAG SQUIB STA-
TUS. All damaged, faulty, or non-deployed supple-
mental restraints which are replaced on vehicles
are to be handled and disposed of properly. If an
airbag or seat belt tensioner unit is faulty or dam-
aged and non-deployed, refer to the Hazardous
Substance Control System for proper disposal. Be
certain to dispose of all non-deployed and deployed
supplemental restraints in a manner consistent with
state, provincial, local and federal regulations.
(3) Next, remove the deployed supplemental
restraints from the vehicle. Refer to the appropriate
service removal procedures.
(4) You may need to vacuum the interior of the
vehicle a second time to recover all of the powder.
STANDARD PROCEDURE - VERIFICATION TEST
The following procedure should be performed using
a DRBIIItscan tool to verify proper supplemental
restraint system operation following the service or
replacement of any supplemental restraint system
component.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS ORSERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) During the following test, the battery negative
cable remains disconnected and isolated, as it was
during the supplemental restraint system component
removal and installation procedures.
(2) Be certain that the DRBIIItscan tool contains
the latest version of the proper DRBIIItsoftware.
Connect the DRBIIItto the 16-way Data Link Con-
nector (DLC). The DLC is located on the driver side
lower edge of the instrument panel, outboard of the
steering column (Fig. 5).
(3) Turn the ignition switch to the On position and
exit the vehicle with the DRBIIItscan tool.
(4) Check to be certain that nobody is in the vehi-
cle, then reconnect the battery negative cable.
(5) Using the DRBIIIt, read and record the active
(current) Diagnostic Trouble Code (DTC) data.
(6) Next, use the DRBIIItto read and record any
stored (historical) DTC data.
(7) If any DTC is found in Step 5 or Step 6, refer
to the appropriate diagnostic information.
(8) Use the DRBIIItto erase the stored DTC data.
If any problems remain, the stored DTC data will not
erase. Refer to the appropriate diagnostic informa-
tion to diagnose any stored DTC that will not erase.
Fig. 4 Vacuum Heater and A/C Outlets - Typical
Fig. 5 16-Way Data Link Connector - Typical
1 - 16-WAY DATA LINK CONNECTOR
2 - BOTTOM OF INSTRUMENT PANEL
DRRESTRAINTS 8O - 9
RESTRAINTS (Continued)

If the stored DTC information is successfully erased,
go to Step 9.
(9) Turn the ignition switch to the Off position for
about fifteen seconds, and then back to the On posi-
tion. Observe the airbag indicator in the instrument
cluster. It should illuminate for six to eight seconds,
and then go out. This indicates that the supplemen-
tal restraint system is functioning normally and that
the repairs are complete. If the airbag indicator fails
to light, or lights and stays on, there is still an active
supplemental restraint system fault or malfunction.
Refer to the appropriate diagnostic information to
diagnose the problem.
ACM COVER
REMOVAL
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be removed to access the ACM for service.
(Refer to 23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry each side of the ACM
cover away from the instrument panel at each side of
the center bracket on the floor panel transmission
tunnel far enough to disengage the two snap clip
retainers from the instrument panel receptacles (Fig.
6).
(3) Remove the ACM cover from the instrument
panel.
INSTALLATION
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be reinstalled following ACM service. (Refer
to 23 - BODY/INTERIOR/FLOOR CONSOLE -
INSTALLATION).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Position the ACM cover to the instrument
panel (Fig. 6).
(2) Align the snap clip retainer on each side of the
ACM cover with the instrument panel receptacle at
each side of the center bracket on the floor panel
transmission tunnel.
(3) Using hand pressure, press firmly and evenly
on the outside of the ACM cover over each snap clip
retainer location until each retainer is fully engaged
in its instrument panel receptacle.
(4) Reconnect the battery negative cable.
Fig. 6 ACM Cover Remove/Install
1 - INSTRUMENT PANEL RECEPTACLE (2)
2 - ACM COVER
8O - 10 RESTRAINTSDR
RESTRAINTS (Continued)

AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is also some-
times referred to as the Occupant Restraint Control-
ler (ORC) (Fig. 7). The ACM is concealed below the
instrument panel center stack in the passenger com-
partment of the vehicle, where it is secured by three
screws to a stamped steel mounting bracket welded
onto the top of the floor panel transmission tunnel
just forward of the instrument panel center support
bracket. Concealed within a hollow in the center of
the die cast aluminum ACM housing is the electronic
circuitry of the ACM which includes a microproces-
sor, an electronic impact sensor, an electronic safing
sensor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ACM housing with four screws to enclose and protect
the internal electronic circuitry and components.
An arrow printed on the label on the top of the
ACM housing provides a visual verification of the
proper orientation of the unit, and should always be
pointed toward the front of the vehicle. The ACM
housing has integral mounting flanges on three cor-
ners. The mounting flange to the left of the connector
receptacle has an integral locating pin on its lower
surface. Both left side flanges have round mounting
holes, while the flange on the right side has a slotted
mounting hole. A molded plastic electrical connector
with two receptacles, one containing twenty-four ter-
minal pins and the other containing thirty-two termi-
nal pins, exits the rearward facing side of the ACM
housing. These terminal pins connect the ACM to the
vehicle electrical system through two dedicated takeouts and connectors of the instrument panel wire
harness.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. In addi-
tion, there are unique versions of the ACM for light
and heavy-duty models, and for vehicles with or
without the optional side curtain airbags. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault, or in some
cases for the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
In standard cab models, the ACM also monitors a
resistor multiplexed input from the passenger airbag
on/off switch and provides a control output for the
Off indicator in the switch through a passenger air-
bag indicator driver circuit. If the passenger airbag
on/off switch is set to the Off position, the ACM turns
on the passenger airbag on/off switch Off indicator
and will internally disable the passenger airbag from
being deployed. The ACM also turns on the on/off
switch Off indicator for about seven seconds each
time the ignition switch is turned to the On position
as a bulb test. Following the bulb test, the ACM con-
trols the status of the Off indicator based upon the
Fig. 7 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - LABEL
4 - CONNECTOR RECEPTACLE (2)
DRRESTRAINTS 8O - 11