Impact Sensor: Description and Operation

WARNING: Vehicle sensor orientation is critical for proper system operation. If a vehicle equipped with an air bag system has been involved in a crash where the fenders or grille area have been damaged, inspect the sensor mounting brackets for deformation. If damaged, the sensor should be replaced whether or not the air bag is deployed. In addition, ensure that the body structure in the area of the sensor mounting is restored to its original condition.

DESCRIPTION

The air bag sensors each consist of:
- A sensing mass
- A bias magnet
- A cylindrical tube
- Two electrical contacts

OPERATION










During normal operation, the bias magnet holds the sensing mass in place. The two electrical contacts remain open during normal operation. Upon impact, the sensing mass pulls away from the bias magnet and rolls down the cylinder toward the electrical contacts. When the sensing mass hits the electrical contacts, it completes the air bag deployment circuit.

The air bag deployment circuit is engaged when the safing sensor completes the power circuit while the LH or RH radiator primary crash front air bag sensor and bracket complete the ground circuit to the igniter to deploy the air bags.

Unless the air bag sensor is damaged during impact, the sensing mass returns to its original position after making contact.