SRS Sensor Module

SRS Sensor Module




The sensor module contains the following:
^ Twin piezoelectric sensor elements which detect deceleration/collision signals.
^ Microprocessors which evaluate collision signals and activate the airbags and pyrotechnical seat belt tensioners.
^ A memory function which stores system fault information even when power has been interrupted (which facilitates fault-tracing).
^ Back-up power unit.

SRS Sensor Module, General
The sensor elements detect a combination of G-force and duration. To activate the system the sensor module must detect a high G-force and prolonged deceleration. The sensor module will not, for example, activate the system after a hammer blow (high G-force, short duration).

A collision violently decelerates the car. The sensor module determines whether the collision is sufficiently powerful to activate the system. If this is the case the sensor module activates the gas generators. The airbags are inflated and the seat belts are tensioned.

The sensor module also has a back-up power function which stores enough power to allow the system to operate even if battery power is interrupted. This can happen if cabling is trapped or the battery is damaged in a collision. There is power for a maximum of 10 seconds after power is interrupted or the ignition is switched off. This power is enough to trigger all igniters within 100 ms of a collision taking place and battery power being interrupted.

It is important that the sensor module be securely mounted onto the bodywork if the sensor module is to operate properly. Otherwise it will only register its own deceleration, not deceleration from the beginning of the collision. Electrical connection to ground is through the ground terminal which is fixed by one of the mounting screws. It is therefore very important that the mounting screws are in good contact with the bodywork. When installing the stated torque must not be exceeded.