1998 DODGE RAM 1500 Ignition system

POWER WINDOWS
TABLE OF CONTENTS
page page
POWER WINDOWS
DESCRIPTION.........................19
OPERATION...........................19
DIAGNOSIS AND TESTING - POWER
WINDOWS...........................19
WINDOW MOTOR
REMOVAL.............................20WINDOW SWITCH
DIAGNOSIS AND TESTING - WINDOW
SWITCH............................20
REMOVAL.............................20
INSTALLATION.........................21
POWER WINDOWS
DESCRIPTION
The power window system allows each of the door
windows to be raised and lowered electrically by
actuating a switch on each door panel. A master
switch on the drivers door allows the driver to raise
or lower each of the passenger door windows and to
lock out the individual switches on the passenger
doors from operation. The power window system
receives battery feed through a fuse in the Integrated
Power Module (IPM) and a circuit breaker located in
the instrument panel wiring harness near the park
brake pedal, only when the ignition switch is in the
RUN or ACCESSORY position.
OPERATION
WINDOW SWITCH
The power window switches control the battery
and ground feeds to the power window motors. The
passenger door power window switches receive their
battery and ground feeds through the circuitry of the
drivers window switch. When the power window lock-
out switch is in the Lock position, the battery feed
for the passenger door window switches is inter-
rupted.
WINDOW MOTOR
Window motors use permanent type magnets. The
B+ and ground applied at the motor terminal pins
will cause the motor to rotate in one direction.
Reversing current through the motor terminals will
cause the motor to rotate in the opposite direction.
DIAGNOSIS AND TESTING - POWER
WINDOWS
WIRING VOLTAGE TEST
The following wiring test determines whether or
not voltage is continuous through the body harness
to the front switch.
(1) Remove the Driver Door Module (Refer to 8 -
ELECTRICAL/POWER LOCKS/DOOR MODULE -
REMOVAL).
(2) Disconnect wire connector from back of power
window switch.
(3) Switch ignition to the ON position.
(4) Connect the clip end of a 12 volt test light to
Pin 14 of the window switch harness connector.
Touch the test light probe to Pin 10.
²If the test light illuminates, the wiring circuit
between the battery and switch is OK.
²If the lamp does not illuminate, first check the
fuse in the Integrated Power Module (IPM). Check
the circuit breaker located near the park brake
pedal. If fuse and circuit breaker are OK, then check
for a broken wire.
Refer to the appropriate wiring information.
POWER WINDOW MOTOR TEST
If the power window motor is receiving proper cur-
rent and ground and does not operate, proceed with
motor test.
(1) Remove front door trim panel as necessary to
gain access to power window motor wire connector
(Refer to 23 - BODY/DOOR - FRONT/TRIM PANEL -
REMOVAL).
(2) Disconnect power window motor wire connector
from door harness.
(3) Using two jumper wires, connect one to a bat-
tery (+) source and the other to a good ground (-).
(4) Connect the Negative (-) jumper probe to one of
the motor connector terminals.
DRPOWER WINDOWS 8N - 19

into the passenger airbag door on the instrument
panel above the glove box (Fig. 2). Vehicles with the
airbag system can also be identified by the airbag
indicator, which will illuminate in the instrument
cluster for about six seconds as a bulb test each time
the ignition switch is turned to the On position. A
pyrotechnic-type seat belt tensioner is integral to the
front outboard seat belt retractors mounted on each
lower B-pillar of all models equipped with dual front
airbags.
²Side Curtain Airbags- Optional side curtain
airbags are available for this model when it is also
equipped with dual front airbags. This airbag systemis a passive, inflatable, Supplemental Restraint Sys-
tem (SRS) and vehicles with this equipment can be
readily identified by a molded identification trim but-
ton with the ªSRS - AIRBAGº logo located on the
headliner above each B-pillar (Fig. 2).
The supplemental restraint system includes the
following major components, which are described in
further detail elsewhere in this service information:
²Airbag Control Module- The Airbag Control
Module (ACM) is also sometimes referred to as the
Occupant Restraint Controller (ORC). The ACM is
located on a mount on the floor panel transmission
tunnel, below the center of the instrument panel.
Fig. 1 Supplemental Restraint System
1 - AIRBAG CONTROL MODULE
2 - PASSENGER AIRBAG
3 - PASSENGER AIRBAG ON/OFF SWITCH (STD CAB ONLY)
4 - DRIVER AIRBAG5 - SIDE CURTAIN AIRBAG (2)
6 - SIDE IMPACT SENSOR (2 - W/SIDE CURTAIN AIRBAGS
ONLY)
7 - SEAT BELT TENSIONER (2)
DRRESTRAINTS 8O - 3
RESTRAINTS (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)

ment in the event of an accidental deployment. When
handling a non-deployed seat belt tensioner, take
proper care to keep fingers out from under the
retractor cover and away from the seat belt webbing
where it exits from the retractor cover. In addition,
the supplemental restraint system should be dis-
armed whenever any steering wheel, steering col-
umn, seat belt tensioner, airbag, impact sensor, or
instrument panel components require diagnosis or
service. Failure to observe this warning could result
in accidental airbag deployment and possible per-
sonal injury.
All damaged, faulty or non-deployed airbags and
seat belt tensioners which are replaced on vehicles
are to be handled and disposed of properly. If an air-
bag or seat belt tensioner unit is faulty or damaged
and non-deployed, refer to the Hazardous Substance
Control System for proper disposal. Dispose of all
non-deployed and deployed airbags and seat belt ten-
sioners in a manner consistent with state, provincial,
local and federal regulations.
SUPPLEMENTAL RESTRAINT STORAGE
Airbags and seat belt tensioners must be stored in
their original, special container until they are used
for service. Also, they must be stored in a clean, dry
environment; away from sources of extreme heat,
sparks, and high electrical energy. Always place or
store any airbag on a surface with its trim cover or
airbag cushion side facing up, to minimize movement
in case of an accidental deployment.
STANDARD PROCEDURE - SERVICE AFTER A
SUPPLEMENTAL RESTRAINT DEPLOYMENT
Any vehicle which is to be returned to use follow-
ing a supplemental restraint deployment, must have
the deployed restraints replaced. In addition, if the
driver airbag has been deployed, the clockspring
must be replaced. If the passenger airbag is
deployed, the passenger airbag door must be
replaced. The seat belt tensioners are deployed by
the same signal that deploys the driver and passen-
ger airbags and must also be replaced if either front
airbag has been deployed. If a side curtain airbag
has been deployed, the complete airbag unit, the
headliner, as well as the upper A, B, and C-pillar
trim must be replaced. These components are not
intended for reuse and will be damaged or weakened
as a result of a supplemental restraint deployment,
which may or may not be obvious during a visual
inspection.
It is also critical that the mounting surfaces and/or
mounting brackets for the Airbag Control Module
(ACM) and the side impact sensors be closely
inspected and restored to their original conditions fol-lowing any vehicle impact damage. Because the ACM
and each impact sensor are used by the supplemental
restraint system to monitor or confirm the direction
and severity of a vehicle impact, improper orientation
or insecure fastening of these components may cause
airbags not to deploy when required, or to deploy
when not required.
All other vehicle components should be closely
inspected following any supplemental restraint
deployment, but are to be replaced only as required
by the extent of the visible damage incurred.
AIRBAG SQUIB STATUS
Multistage airbags with multiple initiators (squibs)
must be checked to determine that all squibs were
used during the deployment event. The driver and
passenger airbags in this model are deployed by elec-
trical signals generated by the Airbag Control Mod-
ule (ACM) through the driver or passenger squib 1
and squib 2 circuits to the two initiators in the air-
bag inflators. Typically, both initiators are used and
all potentially hazardous chemicals are burned dur-
ing an airbag deployment event. However, it is possi-
ble for only one initiator to be used due to an airbag
system fault; therefore, it is always necessary to con-
firm that both initiators have been used in order to
avoid the improper handling or disposal of poten-
tially live pyrotechnic or hazardous materials. The
following procedure should be performed using a
DRBIIItscan tool to verify the status of both airbag
squibs before either deployed airbag is removed from
the vehicle for disposal.
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 the Hazardous Sub-
stance Control System for proper disposal proce-
dures. Dispose of all non-deployed and deployed
airbags in a manner consistent with state, provin-
cial, local, and federal regulations.
(1) 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.
(2) Turn the ignition switch to the On position.
(3) Using the DRBIIIt, read and record the active
(current) Diagnostic Trouble Code (DTC) data.
Using the active DTC information, refer to theAir-
bag Squib Statustable to determine the status of
both driver and/or passenger airbag squibs.
DRRESTRAINTS 8O - 7
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

resistance of the input from the on/off switch. The
ACM will also set and/or store a DTC for faults it
detects in the passenger airbag on/off switch circuits,
and will turn on the airbag indicator in the EMIC if
a fault has been detected.
The ACM receives battery current through two cir-
cuits; a fused ignition switch output (run) circuit
through a fuse in the Integrated Power Module
(IPM), and a fused ignition switch output (run-start)
circuit through a second fuse in the IPM. The ACM
receives ground through a ground circuit and take
out of the instrument panel wire harness. This take
out has a single eyelet terminal connector that is
secured by a ground screw to the instrument panel
support structure. These connections allow the ACM
to be operational whenever the ignition switch is in
the Start or On positions.
The ACM also contains an energy-storage capaci-
tor. When the ignition switch is in the Start or On
positions, this capacitor is continually being charged
with enough electrical energy to deploy the supple-
mental restraint components for up to one second fol-
lowing a battery disconnect or failure. The purpose of
the capacitor is to provide backup supplemental
restraint system protection in case there is a loss of
battery current supply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. The
electronic impact sensors are accelerometers that
sense the rate of vehicle deceleration, which provide
verification of the direction and severity of an
impact. On models equipped with optional side cur-
tain airbags, the ACM also monitors inputs from two
remote side impact sensors located within both the
left and right B-pillars to control deployment of the
side curtain airbag units.
The safing sensor is an electronic accelerometer
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safing
sensor is used to verify the need for a supplemental
restraint deployment by detecting impact energy of a
lesser magnitude than that of the primary electronic
impact sensors, and must exceed a safing threshold
in order for the airbags to deploy. Vehicles equipped
with optional side curtain airbags feature a second
safing sensor within the ACM to provide confirma-
tion to the ACM microprocessor of side impact forces.
This second safing sensor is a bi-directional unit that
detects impact forces from either side of the vehicle.
Pre-programmed decision algorithms in the ACM
microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection
and, based upon the severity of the monitored impact
and the status of the passenger airbag on/off switchinput, determines the level of front airbag deploy-
ment force required for each front seating position.
When the programmed conditions are met, the ACM
sends the proper electrical signals to deploy the dual
multistage front airbags at the programmed force
levels, the front seat belt tensioners and, if the vehi-
cle is so equipped, either side curtain airbag unit.
The hard wired inputs and outputs for the ACM
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the PCI data bus network,
or the electronic message inputs to and outputs from
the ACM. The most reliable, efficient, and accurate
means to diagnose the ACM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
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.
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, NEVER STRIKE OR DROP THE AIRBAG
CONTROL MODULE, AS IT CAN DAMAGE THE
IMPACT SENSOR OR AFFECT ITS CALIBRATION.
THE AIRBAG CONTROL MODULE CONTAINS THE
IMPACT SENSOR, WHICH ENABLES THE SYSTEM
TO DEPLOY THE SUPPLEMENTAL RESTRAINTS. IF
AN AIRBAG CONTROL MODULE IS ACCIDENTALLY
DROPPED DURING SERVICE, THE MODULE MUST
BE SCRAPPED AND REPLACED WITH A NEW UNIT.
FAILURE TO OBSERVE THIS WARNING COULD
RESULT IN ACCIDENTAL, INCOMPLETE, OR
IMPROPER SUPPLEMENTAL RESTRAINT DEPLOY-
MENT.
8O - 12 RESTRAINTSDR
AIRBAG CONTROL MODULE (Continued)