Restraints Control Module (RCM): Notes

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow these instructions may result in the inadvertent deployment of the safety canopy and risk of personal injury.

WARNING: The 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 is restored to its original condition.

CAUTION: When installing a new restraints control module (RCM), always make sure the correct RCM is being installed. The RCM 40-pin connector is keyed differently for vehicles with safety canopies and side air bags than the 40-pin connector for vehicles without safety canopies and side air bags. Do not force the 40-pin connector onto the RCM. If the connector is forced onto the RCM, damage to the RCM and/or connector will occur.

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 carries out the following functions:

deploys the air bag(s) in the event of a deployable crash.
activates the safety belt buckle pretensioners to remove slack from the safety belt.
monitors the 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 instrument cluster module to activate a chime if the air bag indicator is not available and another SRS fault exists.

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 prove out by lighting for 6 seconds and then off for 2 seconds. After the prove out, the air bag indicator will then flash the 2-digit LFC if a SRS fault exists. The air bag indicator will flash the LFC 5 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 DLC, to the scan tool. If the air bag indicator does not function, and the system detects a fault condition, the RCM will signal the instrument cluster module to activate an audible chime. The chime is a series of 5 sets of 5 tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.

LFCs are prioritized. If 2 or more faults occur at the same time, the fault having the highest priority will be displayed. After that fault has been corrected, the next highest priority fault will be displayed.

The RCM includes a backup power supply. This feature provides 150 ms of backup power to deploy the front air bags and pretensioners in the event that the ignition circuit is lost or damaged during impact.

The backup power supply will deplete its stored energy approximately one minute after the battery ground cable is disconnected.