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Belt buckle sensor

Belt buckle sensor


The role of the belt buckle sensor is to detect whether or not the buckle is locked. Based on the information from the belt buckle sensor, the control module determines how the ignition circuits to the seat-belt tensioners and front airbags shall be activated. See SRS control module .

The belt buckle sensor consists of a Hall sensor (1) and a permanent magnet (2). The sensor reads the magnet flow in the permanent magnet. When the belt is unlocked, there is a metal brace over the permanent magnet. When the belt tongue (3) is set, the metal is moved away from the magnet. The magnetic field that reaches the sensor is then changed.


The control module supplies a current to the Hall sensor every 400 ms and checks how much current is passing through the sensor. The current passing through the sensor is dependent on the magnetic flow affecting it.

Position Min value Max value
Unlocked

2.0 mA

5.0 mA

Locked

12.0 mA

15.0 mA



The belt buckle sensors can be diagnosed using Tech2.