Restraints and Safety Systems: Description and Operation

Seat Track Position Sensor

Description






The seat track position sensor (2) is a hall effect type sensor used on some vehicles. This sensor consists of a hall effect integrated circuit chip encased in potting material within a cavity of the molded plastic sensor housing.

The sensor housing has a mounting slot containing an integral latch feature (1) and slides and latches onto a stamped metal blade type bracket located on the inboard side of the upper inboard seat adjuster track near the rear of both the passenger and driver front seats. A molded connector receptacle (3) integral to the sensor housing is connected to the vehicle electrical system through a connector and take out of the seat wire harness beneath the front seat cushion frame.

The seat track position sensor cannot be adjusted or repaired and, if ineffective or damaged, the entire sensor must be replaced.

Operation

The seat track position sensor is designed to provide a seat position data input to the occupant restraint controller indicating whether the driver or passenger front seat is in a full forward or a not full forward position. The ORC uses this data as an additional logic input for use in determining the appropriate deployment force to be used when deploying the multistage front airbags.

The seat track position sensor receives a nominal five volt supply from the ORC. The sensor communicates the seat position by modulating the voltage returned to the ORC on a sensor data circuit. The ORC also monitors the condition of the sensor circuits and will store a diagnostic trouble code for any fault that is detected. The ORC sends messages over the CAN data bus to control the illumination of the airbag indicator in the electromechanical instrument cluster, also known as the cab compartment node.

The hard wired circuits between the seat track position sensor and the ORC may be diagnosed using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the seat track position sensor or the electronic controls and communication between other modules and devices that provide features of the supplemental restraint system. The most reliable, efficient, and accurate means to diagnose the seat track position sensor or the electronic controls and communication related to seat track position sensor operation requires the use of a diagnostic scan tool.