Restraints and Safety Systems: Description and Operation
Restraints Control Module (RCM)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 serious personal injury.
- 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 is restored to its original condition. Failure to follow these instructions may increase the risk of serious personal injury or death in a collision.
CAUTION: When installing a new restraints control module (RCM), it is necessary to carry out programmable module installation (PMI). System failure may occur if PMI is not carried out. See PROGRAMMABLE MODULE INSTALLATION.
NOTE: When installing a new RCM, always make sure the correct RCM is being installed. If an incorrect RCM is installed, erroneous DTCs will result.
The RCM 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 in the event of a deployable collision
- activates the driver and passenger retractor pretensioner(s) to control the tension of the driver and passenger safety belts in the event of a deployable collision
- sends a message to the instrument cluster module to illuminate the air bag warning indicator if a fault is detected
- Communicates through the DLC the current or historical DTCs.
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 six seconds and then off for two seconds. After the prove out, the air bag indicator will then flash the two-digit LFC if a SRS fault exists. 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 DLC, to the scantool. 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 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. 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 negative battery cable is disconnected.