Seat Position Sensor
The seat position sensor is used to determine the proximity of a front passenger seat position with respect to the front air bags. The seat position sensor interfaces with the inflatable restraint sensing and diagnostic module (SDM). The state of the seat position sensor allows the inflatable restraint sensing and diagnostic module to disable stage 2 of the front air bag for a front seat that is forward of the forward/rearward point in the seat track travel. The seat position sensor is a hall effect sensor that is mounted on the outboard seat track of the passenger seat. The seat track includes a metal bracket that shunts the seat position sensor magnetic circuit creating 2 states of seat position, the shunted state represents a rearward seat position and the non-shunted state represents a forward position. The seat position sensor provides 2 current ranges, one range for the shunted state and a second range for a non-shunted state which are inputs to the inflatable restraint sensing and diagnostic module. When the inflatable restraint sensing and diagnostic module receives input from a seat position sensor that state 1 threshold is reached (seat is rearward), the inflatable restraint sensing and diagnostic module will enable stage 2 deployment. When state 2 threshold is reached (seat is forward), the inflatable restraint sensing and diagnostic module will disable stage 2 deployment on the side the seat is forward. The inflatable restraint sensing and diagnostic module monitors the seat position sensor circuit and if a fault is detected, the inflatable restraint sensing and diagnostic module will set code B0080 and disable stage 2 frontal deployment. There could be an improper air gap between the seat position sensor and metal bracket causing a fault with no DTC. An improper air gap will form if the sensor is not mounted properly, the bracket the sensor is mounted on is damaged, or the metal track the sensor detects is damaged. As shown above, the Seat Position Sensor (1) and the metal track must be parallel in order to create the proper air gap.