1999 DODGE RAM light

AIR B AG R ESTR AIN T S YSTE M
1999 D odge P ic ku p R 1500
1999 AIR BAG RESTRAINT SYSTEMS
DaimlerChrysler Corp.
Dodge: Ram Pickup
DESCRIPTION & OPERATION
* PLEASE READ THIS FIRST *
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all WARNINGS and SERVICE PRECAUTIONS.
Supplemental Restraint System (SRS) is designed to work in
conjunction with seat belts. SRS helps to reduce the risk or severity
of serious injury during a front-end collision. Driver-side air bag is
stored in a module in steering wheel hub. All models are equipped with
passenger-side air bags. Passenger-side air bag is stored in the
instrument panel, above glove box. All air bags are covered by a pad
bearing the air bag SRS logo.
Air bag(s) inflate and deflate within 1/10th of a second of
impact sensor switches closing. This creates a cushion of air between
driver and steering wheel and passenger and instrument panel.
System consists of an AIR BAG warning light, clockspring,
driver-side and passenger-side air bag modules, Air Bag Control Module
(ACM), one impact sensor (located inside ACM) and an energy reserve
capacitor. The ACM monitors system, stores fault codes (messages) and
provides information to AIR BAG warning light and Data Link Connector
(DLC). When a malfunction occurs, a fault code is stored and AIR BAG
warning light is activated for more than 12 seconds.
When impact sensor registers sufficient deceleration force
during a front-end collision, an electrical charge is sent from ACM to
air bag module inflator via the clockspring. Inflator actuates and
produces nitrogen gas, which inflates air bag(s).
AIR BAG WARNING LIGHT
Whenever ignition switch is in RUN or START position, AIR BAG
warning light on instrument panel will illuminate for 6-8 seconds and
then turn off. This signifies ACM has checked the system and found
that it is functioning properly. If AIR BAG warning light illuminates
for 12 seconds or more, stays on all the time or does not come on, a
system malfunction exists and trouble code will be stored.
IMPACT SENSOR
All models have one impact sensor located inside ACM. Impact
sensor is an accelerometer that measures deceleration. During a front-
end collision, a signal is sent that completes an electrical circuit
to inflators. Inflators actuate and produce nitrogen gas, which
inflates each air bag. Impact sensor is calibrated for a specific
vehicle and react to severity and direction of vehicle impact.
AIR BAG MODULE
WARNING: DO NOT attempt to disassemble air bag modules. Air bag
modules are not serviceable.
Driver-Side
Air bag module is mounted on front face of steering wheel. A

protective cover is fitted to front of air bag module bearing the SRS
air bag logo. Air bag module contains air bag cushion, inflator and
supporting components. Air bag module is a sealed unit and is not
serviceable. The module inflator assembly produces nitrogen gas to
fill air bag cushion when a small amount of current from ACM is
applied to the ignitor assembly. Gas pressure builds and discharges
from inflator through a diffuser and screen assembly, forcing steering
wheel cover to burst along its seams until air bag is fully inflated.
Once air bag cushion is fully inflated, gas escapes from bag through
vents, away from driver.
Passenger-Side
Air bag module is mounted to instrument panel mounting
bracket. Module is covered by a protective door bearing the SRS air
bag logo. When supplied an electrical signal, inflator will discharge
argon gas directly into air bag. When air bag inflates, protective
door will pivot aside allowing air bag to deploy.
AIR BAG CONTROL MODULE (ACM)
ACM is located under instrument panel, on transmission
tunnel. Impact sensor, energy reserve capacitor and On-Board
Diagnostics (OBD) are an integral part of ACM. ACM monitors critical
input and output circuits within air bag system, ensuring they are
operating correctly. Some circuits are tested continuously; others are
checked only under certain conditions. ACM provides information about
air bag system through AIR BAG warning light and Data Link Connector
(DLC). When diagnostic trouble code (fault message) is stored, AIR B\
AG
warning light will be activated for 12 seconds or more.
DATA LINK CONNECTOR (DLC)
DLC is located under left side of instrument panel, left of
steering column. DLC is used to access SRS on-board diagnostics.
CLOCKSPRING
Clockspring connects air bag module to steering column
wiring, completing air bag system circuit. See Fig. 1. Inside
clockspring is a flat, ribbon-like tape of conductive material, which
winds and unwinds with steering wheel movement. Clockspring is the
most fragile part of air bag system. Clockspring must be centered
properly to allow 1 1/2 steering wheel turns in either direction. If
clockspring is not centered properly, it can break from stretching or
fatigue.
Fig. 1: Identifying Clockspring Assembly
Courtesy of DaimlerChrysler Corp.

PASSENGER AIR BAG DISARM (PAD) SWITCH
PAD switch is mounted on instrument panel. Switch allows
passenger-side airbag module to be disarmed when rear facing child
safety seat is being used. PAD switch is operated with ignition key.
SYSTEM OPERATION CHECK
Turn ignition on and observe AIR BAG warning light. AIR BAG
warning light should illuminate for 6-8 seconds and then go out,
indicating system is functioning properly. If AIR BAG warning light
either fails to illuminate or illuminates continuously, a system
malfunction exists. Perform self-diagnostics. See DIAGNOSIS & TESTING.
After completing necessary repairs, turn ignition switch to
ON position. Ensure no one is inside vehicle, then connect negative
battery cable. Using DRB, erase stored Diagnostic Trouble Codes (DTC).\
See DIAGNOSIS & TESTING .
SERVICE PRECAUTIONS
These precautions should be observed when working with air
bag systems:
* Disable air bag system before servicing any air bag system
or steering column component. Failure to do this could
result in accidental air bag deployment and possible
personal injury. See DISABLING & ACTIVATING AIR BAG SYSTEM .
* Back-up power supply maintains deployment voltage for about
2 minutes after battery is disconnected. When disabling air
bag system, always wait at least 2 minutes after
disconnecting battery cables to resume procedure.
* After repairs, ensure AIR BAG warning light works
properly and no system faults are indicated. See
SYSTEM OPERATION CHECK .
* Always wear safety glasses when servicing or handling an
air bag.
* All SRS component fasteners are specially coated and are
designed with a specific function. Never replace SRS
component fasteners with other than original equipment parts.
* Air bag module must be stored in its original special
container until used for service. It must be stored in a
clean, dry, place, away from sources of extreme heat, sparks
and high electrical energy.
* When placing a live air bag on a bench or other surface,
always face air bag and trim cover up, away from surface.
This will reduce motion of module if accidentally deployed.
* After deployment, air bag surface may contain deposits of
sodium hydroxide, which irritates skin. Always wear safety
glasses, rubber gloves, and long-sleeved shirt during
clean-up and wash hands using mild soap and water. Follow
correct disposal procedures. See DISPOSAL PROCEDURES.
* Because of critical system operating requirements, DO NOT
attempt to service any air bag components. Corrections are
only made by replacing defective part.
* Electrical sources should never be allowed near inflator on
back of air bag module.
* When carrying a live air bag module, trim cover should be
pointed away from your body to minimize injury in case of
deployment.
* When testing voltage or continuity at Air Bag Control Module

(ACM), use wire side (not terminal end) of connector.
* DO NOT probe a wire through insulator, as this will damage
it and eventually cause failure.
* When performing electrical tests, prevent accidental
shorting of terminals. Such shorts can damage fuses or
components and may cause a second fault code to set, making
diagnosis of original problem more difficult.
* When diagnosing air bag system, use DRB volt/ohmmeter
unless instructed to use an external volt/ohmmeter. NEVER
use an analog volt/ohmmeter or test light in place of a
digital volt/ohmmeter.
* When using DRB to diagnose an air bag system problem,
operate DRB from outside of vehicle. DO NOT sit inside of
vehicle.
* Never use an ohmmeter to measure resistance of air bag
module. Accidental air bag deployment may occur, causing
personal injury.
* If air bag system is not fully functional for any reason,
vehicle should not be driven until system is repaired and
again becomes operational. DO NOT remove bulbs, modules,
sensors, or other components or in any way disable system
from operating normally. If air bag system is not
functional, park vehicle until it is repaired and functions
properly.
* When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may
exist until computer systems have completed a relearn cycle.
See COMPUTER RELEARN PROCEDURES in GENERAL INFORMATION
before disconnecting battery.
DISABLING & ACTIVATING AIR BAG SYSTEM
WARNING: Wait at least 2 minutes after disconnecting negative battery
cable before servicing air bag system. System reserve
capacitor, integral to ACM, maintains air bag system voltage
for about 2 minutes after battery is disconnected. Servicing
air bag system before 2-minute period may cause accidental
deployment of air bag(s) and possible personal injury. DO NOT\
use computer system memory saving devices. Enough voltage to
deploy air bag(s) may be provided from device.
CAUTION: When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may
exist until computer systems have completed a relearn cycle.
See COMPUTER RELEARN PROCEDURES in GENERAL INFORMATION
before disconnecting battery.
Disabling System
To disable air bag system for repairs, ensure ignition switch
is in OFF position. Disconnect and shield negative battery cable.
After disconnecting negative battery cable, wait at least 2 minutes
for reserve capacitor to discharge before servicing air bag system.
Activating System
Reconnect negative battery cable. From a position clear of air bag(s),\
turn ignition on. Perform system operation check. See
SYSTEM OPERATION CHECK .
DISPOSAL PROCEDURES
DEPLOYED AIR BAG CLEAN-UP

TORQUE SPECIFICATIONS








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Application Ft. Lbs. (N.m)
Steering Wheel Nut ............................... 45 (61)
INCH Lbs. (N.m)
ACM Mounting Screws &
Support Bracket Nuts ........................ 125 (14.0)
Driver-Side Air Bag Module Screws .......... 80-100 (9-11)
Front Impact Sensor Screws ............... 40-50 (4.5-5.6)
PAD Switch Mounting Screws ...................... 20 (2.2)
Passenger-Side Air Bag Module Screws ............ 80 (9.0)









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DIAGNOSIS & TESTING
* PLEASE READ THIS FIRST *
WARNING: Always follow air bag service precautions to avoid air bag
deployment and possible personal injury. Refer to procedure
under SERVICE PRECAUTIONS . After component replacement,
ensure proper system operation. See SYSTEM OPERATION CHECK.
CAUTION: When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may
exist until computer systems have completed a relearn cycle.
See COMPUTER RELEARN PROCEDURES in GENERAL INFORMATION.
NOTE: Although other scan tools are available, manufacturer
recommends using Diagnostic Readout Box (DRB) tester to
access SRS on-board diagnostics. Following diagnosis and
testing procedures are designed for use with DRB.
SELF-DIAGNOSTIC SYSTEM
SRS is monitored by Air Bag Control Module (ACM). ACM
contains safing sensor, an integral sensor in circuitry of system,
which is used to deploy air bag modules.
ACM monitors critical input and output circuits within air
bag system, ensuring they operate correctly. Some circuits are tested
continuously; others are checked under certain conditions. ACM
provides information about air bag system, through AIR BAG warning
light and DRB tester. Each circuit monitored by ACM has a
corresponding fault code or fault message assigned to it.
Active Codes
A code becomes active as soon as a malfunction is detected.
An active trouble code indicates an on-going malfunction. This means
the defect is currently there every time the ACM checks that
circuit/function. An active trouble code can not be erases. Active
codes will automatically erase when the reason for the code has been
corrected.
With the exception of warning light trouble codes or
malfunctions, when a malfunction is detected, AIR BAG warning light
remains illuminated for a minimum of 12 seconds or as long as the
malfunction is present.
Stored Codes
Trouble codes are automatically stored in ACM memory as soon

as the malfunction is detected. A stored code indicates there was an
active code present at some time. However, the code currently may not
be present as an active code, although another active code could be.
When a trouble code occurs, the AIR BAG warning light
illuminates for 12 seconds minimum (even if problem existed for less
than 12 seconds). Code is stored, along with time in minutes it was
active, and number of times ignition has been cycled since problem was
detected.
When and if malfunction ceases to exist, an ignition cycle
count will be initiated for that code. If ignition cycle count reaches
100 without a reoccurrence of the same malfunction, DTC is erased and
that ignition cycle counter is reset to zero. If malfunction reoccurs
before count reaches 100, ignition cycle counter will be reset and DTC
will continue to be a stored code.
If a particular code is not active while performing
diagnostic test for that code, code diagnostic test may not locate the
source of the problem. In this case, stored code can only indicate an
area of system to inspect.
If no obvious problems are found, erase stored codes, and
with ignition on, wiggle wiring harness and connectors. Recheck for
codes periodically as you work through system. This procedure may
uncover a difficult problem to locate.
PRETEST INSPECTION & DIAGNOSTIC PROCEDURE
Following precautions and procedures must be followed:
* Always follow air bag service precautions to avoid air bag
deployment and possible personal injury. Refer to procedure
under See SERVICE PRECAUTIONS.
* After component replacement, ensure proper system operation.
See SYSTEM OPERATION CHECK .
* When testing voltage or continuity at ACM, use terminal side
(not wire end) of connector. DO NOT probe wire through
insulation.
* Always check if any TECH SERVICE BULLETINS (TSBs) apply to
vehicle.
* When using diagnostic charts, DO NOT skip any steps in chart
or incorrect diagnosis may result. Always perform
SYSTEM OPERATION CHECK after repairs are made.
* Always use most current DRB diagnostic program cartridge
available to prevent erroneous codes or test results.
* When using diagnostic charts, use DRB voltmeter unless
instructed to use an external voltmeter. Never use a test
light in place of a voltmeter.
* When performing electrical tests, prevent accidental
shorting of terminals. Such shorts can damage fuses or
components and may cause a second code (message) to be
set, making diagnosis of original problem more difficult.
* Vehicle must have a fully-charged battery and functional
charging system.
* Each time a connector is disconnected, inspect it to ensure
it is in good condition. Always focus on circuit being
tested. Dirt, water and corrosion, are most common problems
in connectors.
* Always disconnect DRB after use.
* Always disconnect DRB before charging battery.
USING DRB
1) Refer to DRB user guide for instructions and assistance
with reading trouble codes and other DRB functions. Under normal
operation DRB will display one of only 2 error messages: User-

NOTE: All active codes must be resolved before diagnosing store
codes.
1) Raise and support vehicle. Start engine and let idle with
transmission in PARK position. Wiggle wiring harness and connectors of
air bag system and rotate steering wheel from stop to stop.
2) Visually inspect related wire harness connectors. Look for
broken, bent, pushed out, spread, corroded or contaminated terminals.
Also, look for chafed, pierced, pinched or partially broken wires.
3) Check for trouble codes as you work through system. If
stored trouble code becomes active, perform appropriate diagnostic
test. If stored code is reproducible, repair or replace wiring
harness, harness connector or terminals or replace component as
necessary.
CLUSTER MESSAGE MISMATCH
NOTE: Perform AIR BAG VERIFICATION TEST after
all repairs. Each time a connector is disconnected, inspect
it to ensure it is in good condition. Always focus on circuit
being tested. Dirt, water and corrosion, are most common
problems in connectors. Due to manufacturer changes in wire
colors, use terminal identification whenever possible.
1) If AIR BAG warning light is on, go to next step. If AIR
BAG warning light is not on, go to step 5).
2) Using DRB, select PASSIVE RESTRAINTS, AIRBAG and MONITOR
DISPLAY. Read WARNING LAMP STATUS. If DRB does not display MIC LAMP
STATUS ON, replace instrument cluster. If DRB displays MIC LAMP STATUS
ON, go to next step.
3) If DRB displays ACM LAMP REQUEST: ON, go to next step. If
DRB does not display ACM LAMP REQUEST: ON, replace instrument cluster.
4) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
NOTE: If AIR BAG warning light is defective, instrument cluster
will flash seat belt light for 30 seconds starting 10 seconds
after bulb check stops.
5) Using DRB, read air bag control module active codes
(messages). If CLUSTER MISMATCH is only active message, go to next
step. If other messages are present, go to appropriate diagnostic test
to continue diagnosis.
6) If seat belt warning light flashes for 30 seconds after
bulb check is complete, replace instrument cluster. If seat belt
warning light does not flashes for 30 seconds after bulb check is
complete, go to next step.
7) Using DRB, select PASSIVE RESTRAINTS, AIRBAG and MONITOR
DISPLAY. Read WARNING LAMP STATUS. If DRB displays ACM LAMP REQUEST:
OFF, go to next step. If DRB does not display ACM LAMP REQUEST: OFF,
replace instrument cluster.
8) If DRB displays MIC LAMP REQUEST: OFF, go to next step. If
DRB does not display MIC LAMP REQUEST: OFF, replace instrument
cluster.
9) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
DRIVER SQUIB CIRCUIT OPEN
NOTE: Perform AIR BAG VERIFICATION TEST after
all repairs. Each time a connector is disconnected, inspect

it to ensure it is in good condition. Always focus on circuit
being tested. Dirt, water and corrosion, are most common
problems in connectors. Due to manufacturer changes in wire
colors, use terminal identification whenever possible.
1) Disconnect battery and wait 2 minutes before proceeding.
Disconnect driver-side air bag module squib connector. Connect a
jumper wire between driver-side air bag (squib) 2-pin connector
terminal No. 1 (Black/Light Blue wire) and terminal No. 2 (Dark
Green/Light Blue wire). Turn ignition on (engine off). Reconnect
battery. Using DRB, read active codes. If DRB displays DRIVER SQUIB
CIRCUIT SHORTED, replace driver-side air bag module. If not, go to
next step.
2) Disconnect clockspring 2-pin connector. Connect a jumper
wire between clockspring 2-pin connector terminals No. 1 (Black/Light
Blue wire) and No. 2 (Dark Green/Light Blue wire). Using DRB, read
active codes. If DRB displays DRIVER SQUIB CIRCUIT SHORTED, replace
clockspring. If not, go to next step.
3) Disconnect battery and wait 2 minutes before proceeding.
Remove jumper wires. Disconnect ACM connector. ACM is located under
instrument panel, on transmission tunnel. Using an ohmmeter, check
resistance between ACM connector terminal No. 6 (Dark Green/Light Blue
wire) and clockspring 2-pin connector terminal No. 2 (Dark Green/Light\
Blue wire). If resistance is less than 5 ohms, go to next step. If
resistance is more than 5 ohms, repair open or high resistance in Dark
Green/Light Blue wire.
4) Check resistance between ACM connector terminal No. 5
(Black/Light Blue wire) and clockspring 2-pin connector terminal No. 1\
(Black/Light Blue wire). If resistance is less than 5 ohms, go to next\
step. If resistance is more than 5 ohms, repair open or high
resistance in Black/Light Blue wire.
5) If there are no potential causes for this DTC remaining,
ACM is assumed to be defective. Replace ACM. See
AIR BAG CONTROL MODULE (ACM) under REMOVAL & INSTALLATION.
DRIVER SQUIB CIRCUIT SHORTED
NOTE: Perform AIR BAG VERIFICATION TEST after
all repairs. Each time a connector is disconnected, inspect
it to ensure it is in good condition. Always focus on circuit
being tested. Dirt, water and corrosion, are most common
problems in connectors. Due to manufacturer changes in wire
colors, use terminal identification whenever possible.
1) Disconnect battery and wait 2 minutes before proceeding.
Ensure driver-side air bag module connector is completely connected
before disconnecting it. If driver-side air bag module connector is
not completely connected, reconnect it. If driver-side air bag
connector is completely connected, go to next step.
2) Disconnect driver-side air bag module. Turn ignition on
(engine off). Reconnect battery. Using DRB, read active codes. If DRB
displays DRIVER SQUIB CIRCUIT OPEN, replace driver-side air bag
module. If not, go to next step.
3) Disconnect clockspring 2-pin connector. Using DRB, read
active codes. If DRB displays DRIVER SQUIB CIRCUIT OPEN, replace
clockspring. If not, go to next step.
4) Turn ignition off, disconnect battery and wait 2 minutes
before proceeding. Disconnect passenger-side air bag module connector.
Using an ohmmeter, check resistance between clockspring 2-pin
connector terminal No. 1 (Black/Light Blue wire) and passenger-side
air bag 2-pin connector terminal "A" (Black/Yellow wire). If
resistance is less than 5 ohms, repair short between Black/Light Blue
wire and Black/Yellow wire. If resistance is more than 5 ohms, go to