ETR Control Module with Airbag, General Information

The Control Device - also known as the Activation Unit, Trigger Device or Crash Sensor - has the function of calculating the severity of a collision impact and if necessary activating the system in time to restrain occupants.

12-Pin Driver's Airbag Control Device (N2/2):

16-Pin Front Passenger's Airbag Control Device (N2/2):

The Control Device, with it's integrated capacitor and voltage transformer, processes vehicle deceleration during frontal collision and is therefore rigidly mounted on the vehicle transmission tunnel. A built-in safety switch, which interrupts the ignition circuits of the driver's airbag and the seat belt tensioner restraint system during normal driving operation, ensures that the airbag and seat belt tensioner can only be activated by actual acceleration. In this way it is possible to prevent malfunctions.

An accelerometer built into the Control Device records the longitudinal deceleration effects on the vehicle and transmits a signal which is suitably processed and passed onto the threshold value switches for evaluation. When the preset activation thresholds of the two threshold value switches are exceeded the final phases are switched through in accordance with the states' called up via the seat belt lock switches (lock tongue in seat belt lock or not in seat belt lock). This causes activation (see table). If the power supply is interrupted during an accident the driver's airbag can still be activated within 100 milliseconds, but not the two seat belt tensioners. In the case of vehicle voltage amounting to less than 9.5 V for longer than 10 seconds the MIL (Malfunction Indicator Lamp) lights up, but will go out when the voltage rises over 10 V.

The housing and the electrical connections are designed in such a way that malfunctions resulting from electrical interference in the vehicle electricity supply caused by the switching on of electrical consuming devices and electromagnetic radiation on public highways can be one hundred percent excluded. New seat belt locks with separate switches and resistors are necessary to find out whether the lock tongues are inserted in the seat belt locks or not. This results in the following activation logic.

Activation Logic of the Driver's Airbag and Seat Belt Tensioner





Explanation:
In the case of a minor accident in which the protection afforded by the Seat Belts is sufficient, only the Seat Belt Tensioners are activated when the 1st activation threshold is exceeded and the lock tongue is inserted in the seat belt lock. If the lock tongues are not inserted in the seat belt locks, the driver's airbag is activated.

Activation Logic of the Driver's / Front Passenger's Airbag and Seat Belt Tensioner





In the case of a minor accident, in which the protection afforded by the Seat Belts is sufficient only the Seat Belt Tensioners are activated when the 1st activation threshold is exceeded and the lock tongue is inserted in the seat belt lock. If the lock tongues are not inserted in the seat belt locks. the driver's and/or front passenger's airbag is activated.

When the 2nd activation threshold is exceeded the driver's and/or front passenger's airbag is activated even if the lock tongue is inserted.

Block Diagram of the Entire Function of the Driver's/Front Passenger's Airbag / Seat Belt Tensioner