Front passenger seat occupied recognition sensor with automatic child seat recognition, function - GF91.60-P-4008-03A

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Models 170, 208, model 202 as of 12/97 version: model 129, 140, 202 as of 6/97 model 210 from 3/97 up to 6/98

Function schematic

Fig 1: Front Passenger Seat Occupied Recognition Sensor With Automatic Child Seat Recognition, Function Schematic Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Front passenger seat occupied recognition

The foil pressure sensor for seat occupied recognition converts the pressure signals resulting from applied force to the seat into resistance signals.

Precise tuning between the weighted surface and the force prevents an occupied signal from being sent by shopping bags, boxes or suitcases. The foil pressure sensor is designed so that a force of 12 kg over a surface with a diameter of 120 mm is required to actuate the occupied signal.

The resistance signals from the pressure sensors are first detected and evaluated by the electronic evaluation circuitry. If an occupied signal is present it is immediately transmitted to the ETR control module with airbag in the form of a digital report for activation of the supplemental restraint equipment on the passenger side.

The seat occupancy is checked every 2.5 s. When the load on the passenger seat is relieved, the occupied signal remains for 2 min. Maintenance of this signal protects against immediate switch-off of the supplemental restraint equipment when the load on the passenger seat is not present for only a short time.

Automatic child seat recognition

The function of the automatic child seat recognition is ensured only with a special type of child seat offered as an MB accessory. The child seat must have a transponder for communication with the inductive child seat recognition in the passenger seat. The MB child seats are equipped with two transponders each, which are installed in the base on the left and right side.

For recognition of the child seat the electronic evaluation circuitry inductively excites the transponders by means of a transmitter antenna in the switching mat. The transponders change the transmitted signal and transfer it back to the two receiver antennas in the switching mat. The electronic evaluation circuitry decodes the transponder signals and signals to the ETR control module with airbag that a child seat is installed using a digital signal.

Different coding of the two transponders allows the electronic evaluation circuitry to also recognize the installation position of the child seat. This information has no significance at present, because the passenger airbag is always inhibited when a child seat is installed regardless of the installation position.