sensor DODGE RAM 2003 Service Repair Manual

then sends the proper ambient temperature mes-
sages to the EVIC, CMTC over the PCI J1850 data
bus.
The temperature function is supported by the
ambient temperature sensor, a wiring circuit, the
Front Control Module, the Programmable Communi-
cations Interface (PCI) data bus, and a portion of the
Electronics module. If any portion of the ambient
temperature sensor circuit fails, the Front Control
Module will self-diagnose the circuit.
For complete circuit diagrams, refer toWiring.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector.
(2) Measure the resistance of the ambient temper-
ature sensor. At 24É C (75É F), the sensor resistance
should be approximately 10.3 kilohms. At 30É C (86É
F), the sensor resistance should be approximately
7.57 kilohms. The sensor resistance should decrease
as the temperature rises. If OK, refer toDiagnosis
and Testing - Ambient Temperature Sensor Cir-
cuitin this group. If not OK, replace the faulty
ambient temperature sensor.
NOTE: The ambient temperature sensor is a very
sensitive device. When testing, be certain the tem-
perature sensor has had time to stabilize (room
temperature) before attempting to read the sensor
resistance. Failure to let the ambient temperature
sensor temperature stabilize could result in a mis-
leading test.
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR CIRCUIT
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector and the Front Control Module wire
harness connector.
(2) Connect a jumper wire between the two termi-
nals of the ambient temperature sensor wire harness
connector.
(3) Check for continuity between the sensor return
circuit and the ambient temperature sensor signal
circuit cavities of the Front Control Module wire har-
ness connector. There should be continuity. If OK, go
to Step 4. If not OK, repair the open sensor return or
signal circuit as required.(4) Remove the jumper wire from the ambient tem-
perature sensor wire harness connector. Check for
continuity between the sensor return circuit cavity of
the Front Control Module wire harness connector
and a good ground. There should be no continuity. If
OK, go to Step 5. If not OK, repair the shorted sen-
sor return circuit as required.
(5) Check for continuity between the ambient tem-
perature sensor signal circuit cavity of the Front
Control Module wire harness connector and a good
ground. There should be no continuity. If OK, refer to
Diagnosis and Testing - Overhead Consolein
this group. If not OK, repair the shorted ambient
temperature sensor signal circuit as required.
REMOVAL
(1) Open the hood.
(2) Disconnect and isolate the battery negative
cable.
(3) Working on the underside of the hood, remove
screw holding sensor to hood panel.
(4) Disconnect the sensor electrical connector and
remove sensor from vehicle.
INSTALLATION
(1) Connect the sensor electrical connector.
(2) Working on the underside of the hood, install
screw holding sensor to hood panel.
(3) Connect the battery negative cable.
(4) Close the hood.
UNIVERSAL TRANSMITTER
DESCRIPTION
Some DR models are equipped with a universal
transmitter transceiver. The universal transmitter is
integral to the Electronic Vehicle Information Center
(EVIC) and the Compass Mini-Trip Computer
(CMTC), which is located in the overhead console.
The only visible component of the universal transmit-
ter are the three transmitter push buttons centered
between the modules push buttons located just rear-
ward of the display screen in the overhead console.
The three universal transmitter push buttons are
identified with one, two or three light indicators so
that they be easily identified.
Each of the three universal transmitter push but-
tons control an independent radio transmitter chan-
nel. Each of these three channels can be trained to
transmit a different radio frequency signal for the
remote operation of garage door openers, motorized
gate openers, home or office lighting, security sys-
tems or just about any other device that can be
equipped with a radio receiver in the 286 to 399
MegaHertz (MHz) frequency range for remote opera-
DRMESSAGE SYSTEMS 8M - 11
AMBIENT TEMP SENSOR (Continued)

less Entry (RKE) system radio frequency transmit-
ters, if equipped.
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 Lockbutton 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 sys-
tem 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 bat-
tery is disconnected. If an RKE transmitter is faulty
or lost, new transmitter vehicle access codes can be
programmed 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. The
PCI data bus network allows the sharing of sensor
information. This helps to reduce wire harness com-
plexity, internal controller hardware, and component
sensor current loads. 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
8N - 2 POWER LOCKSDR
POWER LOCKS (Continued)

POWER MIRROR MOTOR TEST
If the power mirror switch is receiving proper cur-
rent and ground and mirrors do not operate, proceed
with power mirror motor test. Refer to the appropri-
ate 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.
(1) Remove the power mirror switch (Refer to 8 -
ELECTRICAL/POWER LOCKS/DOOR MODULE -
REMOVAL).
(2) Disconnect wire harness connector to power
mirror switch (Fig. 1).
(3) Using two jumper wires:
²Connect one to a 12 volt source
²Connect the other to a good body ground
²Refer to the Mirror Motor Test Chart for proper
wire connections at the switch connector
MIRROR MOTOR TEST CHART
12 VOLTS GROUND MIRROR REACTION
SWITCH CONNECTOR RIGHT LEFT
PIN 1 PIN 2 - UP
PIN 6 PIN 2 - LEFT
PIN 2 PIN 1 - DOWN
PIN 2 PIN 6 - RIGHT
PIN 7 PIN 2 UP -
PIN 4 PIN 2 LEFT -
PIN 2 PIN 7 DOWN -
PIN 2 PIN 4 RIGHT -
(4) If results shown in table are not obtained,
check for open or shorted circuit. Replace mirror
assembly as necessary.
AUTOMATIC DAY / NIGHT
MIRROR
DESCRIPTION
The automatic day/night mirror uses a thin layer
of electrochromic material between two pieces of con-
ductive glass to make up the face of the mirror.
When the mirror switch is in the On position, two
photocell sensors are used by the mirror circuitry to
monitor external light levels and adjust the reflec-
tance of the mirror.
OPERATION
The ambient photocell sensor is located on the for-
ward-facing (windshield side) of the rear view mirror
housing, and detects the ambient light levels outside
of the vehicle. The headlamp photocell sensor is
located inside the rear view mirror housing behind
the mirror glass and faces rearward, to detect the
level of the light being received at the rear window
side of the mirror. When the circuitry of the auto-
matic day/night mirror detects that the difference
between the two light levels is too great (the light
level received at the rear of the mirror is much
higher than that at the front of the mirror), it begins
to darken the mirror.
The automatic day/night mirror circuitry also mon-
itors the transmission using an input from the
backup lamp circuit. The mirror circuitry is pro-
grammed to automatically disable its self-dimming
feature whenever it senses that the transmission
backup lamp circuit is energized.
The automatic day/night mirror is a completely
self-contained unit and cannot be repaired. If faulty
or damaged, the entire mirror assembly must be
replaced.
DIAGNOSIS AND TESTING - AUTOMATIC DAY /
NIGHT 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.
(1) Check the fuse in the Integrated Power Module
(IPM). If OK, go to Step 2. If not OK, repair the
shorted circuit or component as required and replace
the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fuse in the IPM. If
OK, go to Step 3. If not OK, repair the open circuit to
the ignition switch as required.
Fig. 1 POWER MIRROR SWITCH CONNECTOR
8N - 12 POWER MIRRORSDR
POWER MIRRORS (Continued)

(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Unplug the wire harness connector from the auto-
matic day/night mirror (Fig. 2). Connect the battery
negative cable. Turn the ignition switch to the On
position. Check for battery voltage at the fused igni-
tion switch output (run/start) circuit cavity of the
automatic day/night mirror wire harness connector. If
OK, go to Step 4. If not OK, repair the open circuit to
the IPM as required.
(4) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Check for continuity between the ground circuit cav-
ity of the automatic day/night mirror wire harness
connector and a good ground. There should be conti-
nuity. If OK, go to Step 5. If not OK, repair the cir-
cuit to ground as required.
(5) Connect the battery negative cable. Turn the
ignition switch to the On position. Set the parking
brake. Place the transmission gear selector lever in
the Reverse position. Check for battery voltage at the
backup lamp switch output circuit cavity of the auto-
matic day/night mirror wire harness connector. If
OK, go to Step 6. If not OK, repair the open circuit
as required.
(6) Turn the ignition switch to the Off position.
Disconnect the battery negative cable. Plug in theautomatic day/night mirror wire harness connector.
Connect the battery negative cable. Turn the ignition
switch to the On position. Place the transmission
gear selector lever in the Neutral position. Place the
mirror switch in the On (the LED in the mirror
switch is lighted) position. Cover the forward facing
ambient photocell sensor to keep out any ambient
light.
NOTE: The ambient photocell sensor must be cov-
ered completely, so that no light reaches the sen-
sor. Use a finger pressed tightly against the sensor,
or cover the sensor completely with electrical tape.
(7) Shine a light into the rearward facing head-
lamp photocell sensor. The mirror glass should
darken. If OK, go to Step 8. If not OK, replace the
faulty automatic day/night mirror unit.
(8) With the mirror glass darkened, place the
transmission gear selector lever in the Reverse posi-
tion. The mirror should return to its normal reflec-
tance. If not OK, replace the faulty automatic day/
night mirror unit.
REMOVAL
For removal procedures, (Refer to 23 - BODY/IN-
TERIOR/REAR VIEW MIRROR - REMOVAL).
POWER MIRROR SWITCH
DIAGNOSIS AND TESTING - POWER MIRROR
SWITCH
The power mirror switch is included with the
Driver Door Module. (Refer to 8 - ELECTRICAL/
POWER LOCKS/DOOR MODULE - DIAGNOSIS
AND TESTING).
REMOVAL
The power mirror switch is included with the
Driver Door Module. (Refer to 8 - ELECTRICAL/
POWER LOCKS/DOOR MODULE - REMOVAL).
SIDEVIEW MIRROR
REMOVAL
(Refer to 23 - BODY/EXTERIOR/SIDE VIEW MIR-
ROR - REMOVAL).
Fig. 2 Automatic Day/Night Mirror
1 - REAR FACING SENSOR
2 - CONNECTOR
3 - FORWARD FACING SENSOR
4 - SWITCH
DRPOWER MIRRORS 8N - 13
AUTOMATIC DAY / NIGHT MIRROR (Continued)

Impact Airbag Control Modules (SIACM). An airbag
indicator in the ElectroMechanical Instrument Clus-
ter (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 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 problem in the supplemental restraint sys-
tem electrical circuits. Such a problem may cause air-
bags 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 or the SIACM 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 passen-
ger airbags. During 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 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 provide 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 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,
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
dual front airbag system circuits or components,
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. When the SIACM
monitors a problem in any of the side curtain airbag
system circuits or component, it stores a fault code or
DTC in its memory circuit and sends an electronic
message to the ACM, and the ACM sends an elec-
tronic message to the EMIC to turn on the airbag
indicator. Proper testing of the supplemental
restraint system components, the Programmable
Communications Interface (PCI) data bus, the elec-
tronic message inputs to and outputs from the EMIC,
the SIACM, or the ACM, as well as the retrieval or
erasure of a DTC from the ACM, SIACM, 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: DURING AND FOLLOWING ANY SEAT
BELT OR CHILD RESTRAINT ANCHOR SERVICE,
CAREFULLY 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.
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, driver airbag, passenger
airbag, side curtain airbag, or instrument panel com-
ponents require diagnosis or service. Failure to
observe this warning could result in accidental air-
bag deployment and possible personal 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 Side Impact Airbag Control Module
(SIACM) be closely inspected and restored to their
original conditions following any vehicle impact dam-age. Because the ACM and SIACM each contain
impact sensors that 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 supplemen-
tal restraint deployment, but are to be replaced only
as required by the extent of the visible damage
incurred.
CLEANUP PROCEDURE
Following a supplemental restraint deployment,
the vehicle interior will contain a powdery residue.
This residue consists primarily of harmless particu-
late by-products of the small pyrotechnic charge that
initiates the propellant used to deploy a supplemen-
tal restraint. However, this residue may also contain
traces of sodium hydroxide powder, a chemical
by-product of the propellant material that is used to
generate the inert gas that inflates the airbag. Since
sodium hydroxide powder can irritate the skin, eyes,
nose, or throat, be certain to wear safety glasses,
rubber gloves, and a long-sleeved shirt during
cleanup (Fig. 3).
WARNING: IF YOU EXPERIENCE SKIN IRRITATION
DURING CLEANUP, RUN COOL WATER OVER THE
AFFECTED AREA. ALSO, IF YOU EXPERIENCE
IRRITATION OF THE NOSE OR THROAT, EXIT THE
VEHICLE FOR FRESH AIR UNTIL THE IRRITATION
CEASES. IF IRRITATION CONTINUES, SEE A PHYSI-
CIAN.
(1) Begin the cleanup by using a vacuum cleaner
to remove any residual powder from the vehicle inte-
rior. Clean from outside the vehicle and work your
Fig. 3 Wear Safety Glasses and Rubber Gloves -
Typical
DRRESTRAINTS 8O - 7
RESTRAINTS (Continued)

AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is secured with
four screws to the top mounting surface of a stamped
steel bracket welded onto the top of the floor panel
transmission tunnel forward of the instrument panel
center support bracket and below the instrument
panel center stack in the passenger compartment of
the vehicle (Fig. 7). Concealed within a hollow in the
center of the die cast aluminum ACM housing is the
electronic circuitry of the ACM which includes a
microprocessor, an electronic impact sensor, an elec-
tromechanical 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.
The ACM housing has integral mounting flanges
on each side. Two of the mounting flanges, one on
each side, have an integral locating pin on their
lower surface. The left flanges have round mounting
holes, while the flanges on the right side have slotted
mounting holes. An arrow cast into the top of the
ACM housing near the rear provides a visual verifi-
cation of the proper orientation of the unit, and
should always be pointed toward the front of the
vehicle. A molded plastic electrical connector recepta-
cle containing twenty-three terminal pins exits the
rearward facing side of the ACM housing. These ter-
minal pins connect the ACM to the vehicle electrical
system through a dedicated take out and connector of
the instrument panel wire harness.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, andare only serviced as a unit with the ACM. 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 front supplemental restraint sys-
tem logic circuits and controls all of the front supple-
mental 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 front supplemental restraint system electrical
circuits 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, 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
forever.
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 if an impact is detected that is suffi-
cient for an airbag deployment. The ACM also turns
on the on/off switch Off indicator for about seven sec-
onds each time the ignition switch is turned to the
On position as a bulb test. Following the bulb test,
the ACM controls the status of the Off indicator
based upon the 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.
Fig. 7 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - CONNECTOR RECEPTACLE
8O - 10 RESTRAINTSDR

On models equipped with optional side curtain air-
bags, the ACM communicates with both the left and
right Side Impact Airbag Control Modules (SIACM)
over the PCI data bus. The SIACM notifies the ACM
when it has detected a monitored system fault and
stored a DTC in memory for its respective side cur-
tain airbag system, and the ACM sets a DTC and
controls the airbag indicator operation accordingly.
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 capacitor. When the ignition switch is
in the Start or On positions, this capacitor is contin-
ually being charged with enough electrical energy to
deploy the front supplemental restraint components
for up to one second following 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 sensor is an accelerometer that
senses the rate of vehicle deceleration, which pro-
vides verification of the direction and severity of an
impact. The safing sensor is an electromechanical
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safing
sensor is a normally open switch that is used to ver-
ify the need for a front supplemental restraint
deployment by detecting impact energy of a lesser
magnitude than that of the electronic impact sensor,
and must be closed in order for the front airbags or
seat belt tensioners to deploy. A pre-programmed
decision algorithm in the ACM microprocessor deter-
mines when the deceleration rate as signaled by the
impact sensor and the safing sensor indicate an
impact that is severe enough to require front supple-
mental restraint system protection and, based upon
the status of the passenger airbag on/off switch input
and the severity of the monitored impact, determines
what combination of seat belt tensioner and front air-
bag deployment is required for each front seating
position. When the programmed conditions are met,
the ACM sends the proper electrical signals to deploy
the seat belt tensioners and dual front airbags.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: 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,
SIDE CURTAIN AIRBAG, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(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 DISABLE THE
SUPPLEMENTAL RESTRAINT SYSTEM. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
WARNING: THE AIRBAG CONTROL MODULE CON-
TAINS THE IMPACT SENSOR, WHICH ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE AIRBAG CONTROL MODULE, AS IT CAN DAM-
AGE THE IMPACT SENSOR OR AFFECT ITS CALI-
BRATION. 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 FRONT SUPPLEMEN-
TAL RESTRAINT DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) On models with a manual transmission,
remove the floor console from the top of the floor
panel transmission tunnel. (Refer to 23 - BODY/IN-
TERIOR/FLOOR CONSOLE - REMOVAL).
(3) On models with an automatic transmission,
remove the ACM cover from the instrument panel.
DRRESTRAINTS 8O - 11
AIRBAG CONTROL MODULE (Continued)

(Refer to 8 - ELECTRICAL/RESTRAINTS/ACM
COVER - REMOVAL).
(4) Reach through the rearward facing opening
below the instrument panel center stack support
bracket on the top of the floor panel transmission
tunnel to access and disconnect the instrument panel
wire harness connector for the Airbag Control Mod-
ule (ACM) from the ACM connector receptacle located
on the rearward facing side of the module (Fig. 8). To
disconnect the instrument panel wire harness con-
nector from the ACM:
(a) Slide the red Connector Position Assurance
(CPA) lock on the top of the connector toward the
side of the connector.
(b) Depress the connector latch tab and pull the
connector straight away from the ACM connector
receptacle.
(5) From the right side of the floor panel transmis-
sion tunnel, loosen each of the two screws that secure
the right side of the ACM to the bracket on the floor
panel transmission tunnel about 7 millimeters (0.25
inch).
(6) From the left side of the floor panel transmis-
sion tunnel, remove the two screws that secure the
left side of the ACM to the bracket on the floor panel
transmission tunnel.(7) Still working from the left side of the floor
panel transmission tunnel, lift the ACM upward far
enough to disengage the locating pins on the bottom
of the ACM mounting flanges from the locating holes
in the mounting bracket, then slide the ACM toward
the left far enough to disengage the slotted holes in
the right ACM mounting flanges from under the
heads of the two previously loosened right mounting
screws.
(8) Remove the ACM from the left side of the floor
panel transmission tunnel.
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,
SIDE CURTAIN AIRBAG, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(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 DISABLE THE
SUPPLEMENTAL RESTRAINT SYSTEM. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
WARNING: THE AIRBAG CONTROL MODULE CON-
TAINS THE IMPACT SENSOR, WHICH ENABLES
THE SYSTEM TO DEPLOY THE FRONT SUPPLE-
MENTAL RESTRAINTS. NEVER STRIKE OR DROP
THE AIRBAG CONTROL MODULE, AS IT CAN DAM-
AGE THE IMPACT SENSOR OR AFFECT ITS CALI-
BRATION. 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 FRONT SUPPLEMEN-
TAL RESTRAINT DEPLOYMENT AND POSSIBLE
OCCUPANT INJURIES.
(1) Position the Airbag Control Module (ACM) to
the left side of the floor panel transmission tunnel
near the ACM bracket (Fig. 8). When the ACM is cor-
rectly positioned, the arrow on the ACM housing will
be pointed forward in the vehicle.
(2) From the left side of the floor panel transmis-
sion tunnel, slide the ACM toward the right far
enough to engage the slotted holes in the right ACM
mounting flanges under the heads of the two previ-
ously loosened right mounting screws, then engage
Fig. 8 Airbag Control Module Remove/Install
1 - WIRE HARNESS CONNECTOR
2 - AIRBAG CONTROL MODULE
3 - SCREW (4)
4 - FLOOR PANEL TRANSMISSION TUNNEL
8O - 12 RESTRAINTSDR
AIRBAG CONTROL MODULE (Continued)

(SIACM) and its mounting bracket are secured with
four screws to the inside of each B-pillar behind
(standard cab) or above (quad cab) the front outboard
seat belt retractor, and concealed behind the B-pillar
trim (Fig. 50). Concealed within a hollow in the cen-
ter of the die cast aluminum SIACM housing is the
electronic circuitry of the SIACM which includes a
microprocessor and an electronic impact sensor.
The SIACM housing is secured to a die cast (stan-
dard cab) or stamped steel (quad cab) mounting
bracket, which is unique for the right or left side
application of this component. The SIACM should
never be removed from its mounting bracket. The
housing also receives a case ground through this
mounting bracket when it is secured to the vehicle. A
molded plastic electrical connector receptacle that
exits the top of the SIACM housing connects the unit
to the vehicle electrical system through a dedicated
take out and connector of the body wire harness.
Both the SIACM housing and its electrical connection
are sealed to protect the internal electronic circuitry
and components against moisture intrusion.
The impact sensor internal to the SIACM is cali-
brated for the specific vehicle, and is only serviced as
a unit with the SIACM. The SIACM cannot be
repaired or adjusted and, if damaged or faulty, it
must be replaced.
OPERATION
The microprocessor in the Side Impact Airbag Con-
trol Module (SIACM) contains the side curtain airbag
system logic circuits and controls all of the features
of only the side curtain airbag mounted on the same
side of the vehicle as the SIACM. The SIACM 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 by the
SIACM to communicate with the Airbag Control
Module (ACM) 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. The ACM communicates with both
the left and right SIACM over the PCI data bus.
The SIACM microprocessor continuously monitors
all of the side curtain airbag electrical circuits to
determine the system readiness. If the SIACM
detects a monitored system fault, it sets an activeand stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the ACM over the PCI data
bus. The ACM will respond by sending an electronic
message to the EMIC to turn on the airbag indicator,
and by storing a DTC that will indicate whether the
left or the right SIACM has stored the DTC that ini-
tiated the airbag indicator illumination. An active
fault only remains for the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the SIACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
SIACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
The SIACM receives battery current on a fused
ignition switch output (run-start) circuit through a
fuse in the Integrated Power Module (IPM). The
SIACM has a case ground through its mounting
bracket and also receives a power ground through a
ground circuit and take out of the body wire harness.
This take out has a single eyelet terminal connector
that is secured by a ground screw to the body sheet
metal. These connections allow the SIACM to be
operational whenever the ignition switch is in the
Start or On positions. An electronic impact sensor is
contained within the SIACM. The electronic impact
sensor is an accelerometer that senses the rate of
vehicle deceleration, which provides verification of
the direction and severity of an impact. A pre-pro-
grammed decision algorithm in the SIACM micropro-
cessor determines when the deceleration rate as
signaled by the impact sensor indicates a side impact
that is severe enough to require side curtain airbag
protection. When the programmed conditions are
met, the SIACM sends the proper electrical signals to
deploy the side curtain airbag.
The hard wired inputs and outputs for the SIACM
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 SIACM, the PCI data bus net-
work, or the electronic message inputs to and outputs
from the SIACM. The most reliable, efficient, and
accurate means to diagnose the SIACM, the PCI data
bus network, and the electronic message inputs to
and outputs from the SIACM requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
8O - 54 RESTRAINTSDR
SIDE IMPACT AIRBAG CONTROL MODULE (Continued)