Dodge Ram 2004, Руководство по обслуживанию

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3.1 AIRBAG SYSTEM
The airbag system is designed to provide in-
creased driver and passenger protection if the vehi-
cle is involved in a front end or side collisions. The
system is most effective when used in conjunction
with the seat belt system.
On some models the ACM supports Seat Belt
Tensioners, Passenger Airbag Off Switch, and oth-
ers Impact Sensor. It may be necessary to use the
DRBIII
t
to reconfigure the ACM to the vehicle
equipment.
The airbag control module (ACM) is an electronic
module that monitors the airbag system for proper
operation, stores diagnostic trouble code (DTCs),
controls the airbag warning lamp and contains the
sensor and actuator that is responsible for driver,
passenger, and curtain airbag deployment. The
ACM is mounted on a special bracket that is fas-
tened to the floor of the truck at the bottom of the
instrument panel. It is located forward of the con-
sole. The ACM provides diagnostic information
(DTCs) to the technician through the DRBIII
t
via
the PCI bus. Some circuits are tested continuously;
others are checked only under certain circum-
stances. The warning lamp is driven with messages
relayed to the Electro/Mechanical Instrument Clus-
ter (EMIC) from the ACM via the PCI bus.
The AIRBAG warning lamp is the only point at
which “symptoms” of a system malfunction can be
observed by the customer. Whenever the ignition
key is turned to the “run” position, the airbag
control module performs a lamp check by turning
the AIRBAG warning lamp on for 6-8 seconds. If the
lamp remains off, it means that the ACM has
checked the system and found it to be free of
discernible malfunctions. If the lamp remains on,
there could be an active fault in the system or the
circuit that operates the lamp may be shorted to
ground. If the lamp comes on and stays on for a
period longer than 6-8 seconds, then goes off, there
is usually an intermittent problem in the system.
WARNING: THE AIRBAG CONTROL MODULE
CONTAINS THE IMPACT SENSOR, WHICH
ENABLES THE SYSTEM TO DEPLOY THE
AIRBAG. BEFORE ATTEMPTING TO DIAG-
NOSE OR SERVICE ANY AIRBAG SYSTEM
OR RELATED STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPO-
NENTS YOU MUST FIRST DISCONNECT AND
ISOLATE
THE BATTERY NEGATIVE
(GROUND) CABLE. THEN WAIT TWO
MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE FURTHER SYSTEM
SERVICE. THIS IS THE ONLY SURE WAY TO
DISABLE THE AIRBAG SYSTEM. FAILURE
TO DO THIS COULD RESULT IN ACCIDENTAL
AIRBAG
DEPLOYMENT AND POSSIBLE
PERSONAL INJURY OR DEATH.
WARNING: NEVER STRIKE OR KICK THE
AIRBAG CONTROL MODULE, AS IT CAN
DAMAGE THE IMPACT SENSOR OR AFFECT
ITS CALIBRATION. IF AN AIRBAG CONTROL
MODULE
IS ACCIDENTALLY DROPPED
DURING SERVICE, THE MODULE MUST BE
SCRAPPED AND REPLACED WITH A NEW
UNIT. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL
AIRBAG
DEPLOYMENT AND PERSONAL
INJURY OR DEATH.
The DR will have two Airbag Control Modules.
Each ACM is specifically calibrated for one body
type, light duty or heavy duty. To determine the
body types the ACM monitors the PCI Bus for a
message containing the complete VIN. The ACM
uses the 6th digit of the VIN to identify the heavy
duty or light duty vehicle. The 6th digit of the VIN
will be a number 1 for light-duty vehicle and a 2, 3
or 4 for heavy-duty vehicle. If the PCI Bus VIN
message 6th character matches the ACM body type,
the VIN will be stored within 5.6 seconds after
ignition on. After the VIN is stored, the ACM
verifies PCI Bus VIN message within 2.6 seconds
after the ignition is turned on.
If two valid matching PCI Bus VIN messages are
not received within 5.6 seconds the ACM will set a
Missing Original VIN DTC.
If the ACM and PCM module types, 6th character
of the VIN, light-duty or heavy-duty do not match
the Calibration Mismatch DTC will be set.
CAUTION: Therefore, the practice of exchang-
ing
(swapping) airbag control modules,
instrument clusters, powertrain control
modules and other electronic modules in this
vehicle with those removed from another
vehicle must always be avoided.
3.1.1 DRIVER AIRBAG
The airbag protective trim cover is the most
visible part of the driver side airbag system. The
protective trim cover is fitted to the front of the
airbag module and forms a decorative cover in the
center of the steering wheel. The module is
mounted directly to the steering wheel. Located
under the trim cover are the horn switch, the airbag
cushion, and the airbag cushion supporting compo-
nents. The airbag module includes a housing to
which the cushion and hybrid inflator are attached
and sealed. The airbag module cannot be repaired,
and must be replaced if deployed or in any way
damaged.
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GENERAL INFORMATION