Navigator 4WD V8-5.4L DOHC VIN A (2000)
Air Bag Control Module: Description and Operation
The Restraints Control Module (RCM) performs the following functions:
^
signals the inflators to deploy the air bags in the event of a deployable crash.
^
monitors the air bag Supplemental Restraint System (SRS) for faults.
^
illuminates the air bag indicator if a fault is detected.
^
flashes the air bag indicator to indicate the Lamp Fault Code (LFC) detected.
^
communicates through the Data Link Connector (DLC) the current or historical Diagnostic Trouble Codes (DTCs).
^
signals the Generic Electronic Module (GEM) to activate a chime if the air bag indicator is not available and another SRS fault exists.
NOTE: The safing sensor is internal to the RCM and is not repaired separately.
The RCM monitors the SRS for possible faults. If a fault is detected while the ignition switch is in the RUN position, the RCM will illuminate the air bag
indicator located in the instrument cluster.
When the ignition is cycled (turned OFF and then ON), the air bag indicator will remain lit for six seconds and then go out. If an SRS fault exists, the air
bag indicator will then flash a two-digit Lamp Fault Code (LFC). The air bag indicator will flash the LFC five times, then it will remain illuminated for
the rest of the key cycle. The RCM will also communicate the current and historical DTCs through the Data Link Connector (DLC), using a scan tool. If
the air bag indicator does not function, and a system fault is detected, the RCM will signal the GEM to activate the audible chime. The chime is a series
of five sets of five tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.
LFCs are prioritized. If two or more faults occur at the same time, the fault having the highest priority will be displayed first. After the fault has been
corrected, the next highest priority fault will be displayed.
The RCM includes a backup power supply. This feature provides sufficient backup power to deploy the air bags in the event that the ignition circuit is
damaged in a collision before the safing and air bag sensors determine that an air bag deployment is required. The backup power supply will deplete its
stored energy approximately 1 minute after the battery ground cable is disconnected.
Sensor
WARNING: THE RESTRAINTS CONTROL MODULE (RCM) ORIENTATION IS CRITICAL FOR CORRECT SYSTEM
OPERATION. IF A VEHICLE EQUIPPED WITH AN AIR BAG SUPPLEMENTAL RESTRAINT SYSTEM (SRS) HAS BEEN
INVOLVED IN A COLLISION IN WHICH THE CENTER TUNNEL AREA HAS BEEN DAMAGED, INSPECT THE MOUNTING
AND BRACKET FOR DEFORMATION. IF DAMAGED, THE RCM MUST BE REPLACED WHETHER OR NOT THE AIR BAGS
HAVE DEPLOYED. IN ADDITION, MAKE SURE THE AREA OF THE RCM MOUNTING IS RESTORED TO ITS ORIGINAL
CONDITION.
The SRS uses four crash sensors. Two of the sensors are integral to the RCM and not separately serviceable. In addition, there are two side crash
sensors mounted beneath their respective seats. The RCM is mounted to the center tunnel beneath the instrument panel. Mounting orientation is
critical for correct operation of all crash sensors.
