Principles of Operation: Notes

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

During a frontal or side crash, the restraints control module (RCM) may deploy the safety belt retractor pretensioners, side air bag(s) and/or none, one or both stages of the driver/passenger dual-stage air bag based on crash severity and conditions. The fact that the pretensioners or air bags did not deploy for both front seat occupants in a collision does not indicate a fault with the supplemental restraints system (SRS).

In a frontal collision, the front impact severity sensor detects sudden vehicle deceleration and sends an electrical signal to the RCM. The RCM uses the information from the front impact severity sensor, safety belt buckle switches and the occupant classification system module (OCSM) to determine deployment. If deployment is required, the RCM sends voltage and current to the air bag module(s) and safety belt retractor pretensioner(s).

In a side collision, the side impact sensor(s) detects sudden vehicle lateral deceleration and sends an electrical signal to the RCM. The RCM uses the information from the side impact sensor, safety belt buckle switches and the OCSM to determine deployment. If deployment is required, the RCM sends voltage and current to the side air bag module(s) and safety belt retractor pretensioner(s).

The RCM performs a complete system "self-test" during each startup. If a SRS fault exists, the air bag warning indicator will illuminate and remain illuminated for the rest of the key cycle. In addition to the self-test at start up, the RCM continuously monitors all SRS components and circuitry for correct operation. The RCM communicates current and historical DTCs through the data link connector (DLC) using a scan tool. The RCM also communicates to the OCSM on a dedicated high-speed controller area network (HS-CAN) communication system.