Seat-Occupancy Detection, Front Passenger

Seat-Occupancy Detection, Front Passenger

Seat-occupancy detection, front passenger
The front passenger seat occupancy detection detects whether the seat is occupied or not.
The design of the seat occupancy detection depends on the national-market version.
Seat occupancy detector, front passenger (US version):
In accordance with the stipulations of the National Highway Traffic Safety Administration (NHTSA) a small child in a child restraint system on the front passenger seat must be automatically detected. Upon detection, the airbags on the passenger side are automatically deactivated (front-passenger airbag, side airbag, knee airbag). The indicator light for front passenger airbag deactivation lights up.

Functional description
The front passenger seat occupancy detection consists of a seat occupancy mat with a capacitive sensor system and evaluation electronics. The occupancy of the front passenger seat is detected by measuring the capacitive resistance of the human body.
The electronic evaluation unit picks up the change and determines the corresponding status.
The airbags on the front passenger side (front passenger airbag, side airbag, knee airbag) are deactivated automatically when the seat is empty or a small child is detected in the child restraint system provided for this purpose. The indicator light for front passenger airbag deactivation lights up.
If a person of adequate size sitting correctly is detected, the airbags on the front passenger side are activated. The indicator light for the front passenger airbag deactivation does not light up.
The front passenger airbag could deactivate with a youth or adult seated in certain positions (indicator light for passenger airbag deactivation comes on). In these cases, the seat position must be changed until the indicator light for the front passenger airbag deactivation goes out (airbags on the front passenger side are activated). The electronic processing circuit relays status information to the Crash Safety Module in cyclical transmissions. Potential error conditions are stored in the Crash Safety Module's fault memory.
If the seat occupancy mat is defective, the airbags on the front passenger side are automatically disabled (front passenger airbag, knee airbag, side airbag). The indicator light for front passenger airbag deactivation lights up. The following graphic shows the seat occupancy mat with capacitive sensor system using the example F25.







Structure and inner electrical connection
The front passenger seat occupancy detection consists of the following components:
- Seat-occupancy mat with capacitive sensor system
The capacitive sensor system integrated in the seat-occupancy mat is connected to the evaluation electronics in the electronic component.

- Electronic component
In the electronic component, the sensor signals are processed, converted into digital signals and sent in cycles to the crash safety module. The data is transmitted via the LIN bus.
Possible fault statuses of the front passenger seat occupancy detection are saved in the fault memory of the Crash Safety Module.

The front passenger seat occupancy mat is supplied with voltage by the crash safety module (ACSM). (ACSM stands for "Advanced Crash Safety Module", referred to as the "crash safety module").







Diagnosis instructions

Failure of the component:
If the front passenger seat occupancy mat fails, the following behavior is to be expected:
- Fault entry in the crash safety module
- Airbag warning lamp lights up
- Indicator lamp for front passenger airbag deactivation (only for US version)
- Airbags on the front passenger side are automatically deactivated (front passenger airbag, side airbag, knee airbag)

General note
Following replacement of the front passenger seat occupancy mat with capacitive sensor system, the seat occupancy mat must be enabled. A service function is available for initialization:
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.