Seat occupied recognition with automatic child seat recognition, component description - GF91.60-P-4035SX

MODEL 216.3, 221.0 /1 up to 31.5.07 except CODE (494) USA version

MODEL 216.3, 221.0 /1 as of 1.6.07 except CODE (494) USA version with CODE (U18) Automatic child seat recognition (ACSR) up to Model Year 8

Shown on model 221.0

Fig 1: Identifying Front Passenger Seat Occupied And Child Seat Recognition Sensor

Courtesy of MERCEDES-BENZ USA

Location

The seat occupied and automatic child seat recognition is integrated in the seat cushion of the front passenger seat.

Task

The seat occupancy and automatic child seat recognition system is used to determine front passenger seat occupancy for the purpose of issuing a seat belt reminder warning, for weight classification and for detecting a child seat that has been approved and coded by DaimlerChrysler, including its direction of installation.

Design

The seat occupied and automatic child seat recognition consists of a sensor mat inserted into the seat surface of the front passenger seat with an attendant analysis electronic circuit.

The following are located in the sensor mat:

Diaphragm pressure sensors for detecting front passenger seat occupancy
One transmitting antenna at right and left
Two receiving antennas for detecting a child seat

Function

Seat occupied recognition sensor

If the front passenger seat is occupied by a person, the pressure load of the seat area increases. This results in a change in the resistance of the force sensing resistors in the seat occupied and automatic child seat recognition system. If the pressure on the seat surface exceeds a defined value, the evaluation electronics detect that the front passenger seat is occupied by a person and transmit a signal to the restraint systems control unit (N2/7) via the data line. The seat occupied status is permanently monitored. Once the seat is no longer occupied, the occupied signal remains pending for a brief period.

This provides protection from an immediate shut-off of all safety equipment if the weight is removed from the front passenger seat for a short time.

Automatic child seat recognition

The automatic child seat recognition function is only guaranteed to work with a child seat that has been approved and coded by DaimlerChrysler. This child seat must be equipped with 2 transponders (resonators), which are located in its base on the left and right. When a child seat is in position, the signals that are transmitted by the electronic analysis system via the transmitting antennas in the occupancy and automatic child seat recognition system are modified by the resonators in the child seat. These signals are received by the relevant receiving antennas in the occupancy and automatic child seat recognition system and relayed to the electronic analysis system.

The electronic analysis system evaluates the signals and notifies the restraint systems control unit of the instantaneous status with (e.g. Child seat present or not present, Child seat incorrectly positioned).

Through analysis of the two signals it is also possible to clearly determine how the child seat is aligned (in or against the direction of travel).

If the child seat is wrongly positioned, an appropriate message is displayed in the instrument cluster (A1).