Dodge RAM TRUCK 1500 1995 Service Manual page 499

8M - 2 RESTRAINT SYSTEMS
module cover, the airbag cushion and its supporting
components are contained. The airbag module con­
tains a housing to which the cushion and inflator are
attached and sealed. The airbag module is non-ser­
viceable, and must be replaced if deployed or dam­
aged in any way
The inflator assembly is mounted to the back of the
module. The inflator seals the hole in the airbag
cushion so it can discharge the gas it produces di­
rectly into the cushion when supplied with the
proper electrical signal. The protective cover is fitted
to the front of the airbag module and forms a deco­
rative cover in the center of the steering wheel. Upon
airbag deployment, this cover will split horizontally.
S T O R A G E
The airbag module must be stored in its original,
special container until used for service. Also, it must
be stored in a clean, dry environment; away from
sources of extreme heat, sparks, and high electrical
energy. Always place or store the module on a surface
with the trim cover facing up to minimize movement
in case of accidental deployment.
IMPACT SENSOR
The impact sensors provide verification of the di­
rection and severity of the impact. Three impact sen­
sors are used. One is called a safing sensor. It is
located inside the airbag control module (ACM),
which is mounted to a bracket under the instrument
panel on the top of the floor pan transmission tunnel.
The other two sensors are mounted on the inner
fender extension panels behind the grille opening re­
inforcement on the left and right side of the vehicle.
— gft
The impact sensors are threshold sensitive
switches that complete an electrical circuit when an
impact provides a sufficient deceleration force to
close the switch. The sensors are calibrated for the
specific vehicle, and react to the severity and direc­
tion of the impact.
CLOCKSPRING
The clockspring is mounted on the steering column
behind the steering wheel. It is used to maintain a
continuous electrical circuit between the wiring har­
ness and the driver's side airbag module. This assem­
bly consists of a flat, ribbon-like electrically
conductive tape which winds and unwinds with the
steering wheel rotation.
AIRBAG CONTROL MODULE
The airbag control module (ACM) contains the saf­
ing sensor, and monitors the system to determine its
readiness. The ACM contains on-board diagnostics
(OBD), and will light the airbag warning lamp in the
instrument cluster when a monitored airbag system
fault occurs.
The ACM also contains an energy storage capacitor.
This capacitor stores enough electrical energy to de­
ploy the airbag for up to 2 minutes following a bat­
tery disconnect or failure. The purpose of this unit is
to provide airbag protection in a severe secondary
impact if the initial impact has damaged or discon­
nected the battery, but was not severe enough to de­
ploy the airbag.
D I A G N O S I S
A DRB scan tool is required for diagnosis of the air-
bag system. Refer to Airbag System - Body Diagnos­
tic Procedures manual for more information.
AIRBAG SYSTEM CHECK
(1) Disconnect battery negative cable and isolate.
(2) Connect DRB scan tool to ACM diagnostic
6-way connector. The connector is clipped under the
lower left corner of the instrument panel.
(3) From right side of vehicle (away from airbag in
case of accidental deployment), turn the ignition
switch to the ON position. Exit vehicle with DRB.
Use the latest version of the proper DRB cartridge.
(4) After checking that nobody is inside the vehi­
cle, reconnect the negative battery terminal.
(5) Using the DRB, read and record active diagnos­
tic trouble code (DTC) data.
(6) Read and record any stored DTC.
(7) Refer to the Airbag System - Body Diagnostic
Test Procedures manual, if any DTC is found in steps
5
or
6.
(8) Erase stored DTC, if there are no active fault
codes. If problems remain, DTC will not erase.
(9) With the ignition switch in the ON position,
make sure nobody is in the vehicle.
(10) From right side of vehicle, turn the ignition
switch to OFF then ON. Observe airbag warning
lamp on the instrument cluster. It should light for 6
to 8 seconds, then go out; indicating system is func­
tioning normally.
If the airbag warning lamp fails to light, or
lights and stays on, there is a system malfunc­
tion. Refer to the Airbag System - Body Diag­
nostic Test Procedures manual to diagnose the
problem.