Principles of Operation: Notes

WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

In a frontal collision, the front impact severity sensors detects sudden vehicle deceleration and sends an electrical signal to the Restraints Control Module (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 the RCM determines that 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(s), safety belt buckle switches and the OCSM to determine deployment. If the RCM determines that deployment is required, the RCM sends voltage and current to the side air curtains, seat side air bag module(s) and safety belt retractor pretensioner(s).

During a frontal or side crash, the RCM may activate the side air curtains, safety belt retractor pretensioners, seat side air bag(s) and one or both stages of the driver/passenger dual-stage air bag, based on crash severity and conditions. The fact that the safety belt buckle pretensioners, adaptive load limiting retractors or air bags did not activate for both front seat occupants in a collision does not mean that something is wrong with the system.

The RCM performs a "self-test" of the complete Supplemental Restraint System (SRS) during each startup. If a SRS fault exists, the air bag warning indicator will illuminate and remain illuminated for the rest of the ignition cycle. In addition to the self-test at start up, the RCM continuously monitors all of its SRS components and circuitry for correct operation.