Crown Victoria V8-4.6L SOHC VIN W (2005)
Air Bag Control Module: Description and Operation
RESTRAINTS CONTROL MODULE (RCM)
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, a new RCM must be installed whether or not the air bags have deployed. In addition, make sure the
area of the RCM mounting area is restored to its original condition.
NOTE: When installing a new restraints control module (RCM), always make sure the correct RCM is being installed. If an incorrect RCM is installed,
erroneous DTCs will result.
The restraints control module (RCM) is mounted on the center tunnel under the instrument panel. The RCM carries out the following functions:
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Signals the inflators to deploy the air bags in the event of a deployable crash.
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Activates the steering column squib to help reduce the force needed to collapse the steering column.
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Activates the safety belt retractor pretensioners to remove slack from the safety belt.
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Monitors the air bag SRS for faults.
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Illuminates the air bag indicator if a fault is detected.
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Receives information from the front and side impact sensors.
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Sends safety belt buckle status to the instrument cluster for safety belt lamp and belt-minder.
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Flashes the air bag indicator to indicate the lamp fault code (LFC) detected.
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Communicates through the data link connector (DLC) the current or historical diagnostic trouble codes (DTCs).
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Signals the instrument cluster to activate a chime if the air bag indicator is not available and another SRS fault exists.
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Contains an internal safing sensor which is not serviced separately.
The RCM monitors the SRS for possible faults. If a fault is detected while the ignition switch is in the ON 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 a SRS fault exists, the air bag
indicator will then flash the two-digit 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 the diagnostic tool. If the air bag
indicator does not function, and the system detects a fault condition, the RCM will signal the instrument cluster to activate an 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 that 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 air bag deployment is activated. The backup power supply will deplete its stored energy approximately one minute after
the power is removed from the RCM.
