System Operation

In a collision, the sudden deceleration or acceleration is measured by the impact sensors and the accelerometers in the RCM. The RCM evaluates the readings to determine the impact point on the vehicle and whether the deceleration/acceleration readings exceed the limits for firing any of the air bags, pretensioners, and battery disconnect unit. During a collision, the RCM only fires the air bags and pretensioners if the saving function confirms that the data from the impact sensor(s) indicates an impact limit has been exceeded.

The RCM incorporates the following impact thresholds to cater for different accident scenarios:

• Front impact, pretensioners
• Front impact, driver and passenger air bags stage 1, belt unfastened
• Front impact, driver and passenger air bags stage 1, belt fastened
• Front impact, driver and passenger air bags stage 2, belt unfastened
• Front impact, driver and passenger air bags stage 2, belt fastened
• Rear impact
• Driver side impact
• Passenger side impact.

The front impact thresholds increase in severity from pretensioners, through to driver and passenger air bag stage 2, belt fastened.