Air Bag Control Module: Description and Operation

N2/2 Control Module with Side Airbags (50-pin):

The introduction of the side airbag units necessitated once again extending the functions of the control module.

In addition to detecting the longitudinal acceleration to which the car is subjected in a head-on collision which is required for activating the ETRs and airbag units, the 50-pin control module additionally detects:
- the longitudinal acceleration to which the car is subjected in a rear-end collision,
- the lateral acceleration to which the car is subjected in a side-on collision, signalled by the side airbag sensors (A53 and A54), and
- the signals of the seat occupancy recognition provided the car is equipped witn this feature.

The control module additionally features a so-called crash output which can be used not only for the functions of the airbag and ETR restraint systems, but also for activating additional systems, such as emergency call systems. The crash output was not assigned at the date of introduction of the 50-pin control module.

NOTE: If a new control module is installed, it must always then be programmed and parameterized with the hand held tester.

Activation Logic:

Explanatory notes:
If the severity of the accident is only slight and the protection offered by the seat belts is adequate, only the emergency tensioning retractors are activated if the 1st threshold is exceeded, provided the belt latches are inserted in the belt buckles.

The driver airbag is always activated if the 1st threshold is exceeded and the belt latch is not inserted.

The passenger airbag is activated if the 1st threshold is exceeded and the belt latch is not inserted only if additionally the "passenger seat occupied" signal is supplied to the control module (N2/2) by the seat occupancy recognition feature.

The driver airbag is always activated if the 2nd threshold is exceeded and the belt latch is inserted.

The passenger airbag is activated if the 2nd threshold is exceeded and the belt latch is inserted only if additionally the "passenger seat occupied" signal is supplied to the control module (N2/2) by the seat occupancy recognition feature.

The driver side airbag is always activated if the lelt side airbag sensor detects a side-on collision.

The passenger side airbag is activated only if the belt latch is inserted, the right side airbag sensor detects a side-on collision and additionally the "passenger seat occupied" signal is supplied to the control module (N2/2) by the seat occupancy recognition feature.

SRS Block Diagram of Overall Function: