Seat position sensor
| Seat position sensor |
The task of the seat position sensor is to recognise if the seat position is in front of or behind 30 % calculated from the front-most position. Based on the information from the belt buckle sensor, the control unit determines how the ignition circuits to the front airbags is to be activated.
Two leads are connected to the seat position sensor from the SRS control module. These leads are used to supply power and communicate between the seat position sensor and the control module. The sensor also sends voltage to the control module. The level of the voltage depends on whether or not the sensor is actuated.
The seat position sensor consists of a Hall sensor mounted on the part of the seat rail that is mounted to the floor. A permanent magnet strap is mounted on the seat portion of the rail. When the seat is between the front-most position and up to 30 %, the sensor is actuted by the permanent magnet.
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 field affecting it.
| Position (calculated from the front-most position) | Min value | Max value |
|
<30%
|
4 mA
|
7 mA
|
|
>30%
|
12 mA
|
17 mA
|
The seat position sensors can be diagnosed using Tech2.
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