Seat Belt Buckle Switch: Description and Operation

LUMBAR CONTROL SWITCH
The 8-way power seat option includes an electrically operated lumbar support mechanism. A single two-way momentary power lumbar switch is integral with the power seat switches. The power lumbar switch is secured to the back of the seat cushion side shield with screws, and the switch paddle protrudes through a hole to the outside of the shield. The switch paddle is located in a shallow depression molded into the outer surface of the seat cushion side shield that helps to shroud it from unintentional actuation when entering or leaving the vehicle.

The power lumbar switches cannot be adjusted or repaired and, if faulty or damaged, the seat switch assembly must be replaced.

When the power lumbar switch paddle is actuated, a battery feed and a ground path are applied through the switch contacts to the power lumbar adjuster motor. The motor operates to move the lumbar adjuster through its drive unit in the selected direction until the switch is released, or until the travel limit of the adjuster is reached. When the switch is moved in the opposite direction, the battery feed and ground path to the motor are reversed through the switch contacts. This causes the motor to run in the opposite direction.

The power lumbar switch should not be held applied in either direction after the adjuster has reached its travel limit. The power lumbar adjuster motor contains a self-resetting circuit breaker to protect it from overload. However, consecutive or frequent resetting of the circuit breaker must not be allowed to continue, or the motor may be damaged.

SEAT BELT SWITCH
The seat belt switch is a small, normally closed, single pole, single throw, leaf contact, momentary switch. Only one seat belt switch is installed in the vehicle, and it is integral to the buckle of the driver seat belt buckle-half, located near the inboard side of the driver side front seating position. The seat belt switch is connected to the vehicle electrical system through a two-wire pigtail wire and connector on the seat belt buckle-half, which is connected to a wire harness connector and take out of the body wire harness.

The seat belt switch cannot be adjusted or repaired and, if faulty or damaged, the entire driver seat belt buckle-half unit must be replaced.

The seat belt switch is designed to control a path to ground for the seat belt switch sense input of the Electro-Mechanical Instrument Cluster (EMIC). when the driver side seat belt tip-half is inserted in the seat belt buckle, the switch opens the path to ground; and, when the driver side seat belt tip-half is removed from the seat belt buckle, the switch closes the ground path. The switch is actuated by the latch mechanism within the seat belt buckle. The EMIC monitors the driver seat belt switch status, then controls the seatbelt indicator and sends hard wired chime requests to the Central Timer Module (CTM) based upon that input.

The seat belt switch receives ground through its pigtail wire connection to the body wire harness from another take out of the body wire harness. An eyelet terminal connector on that ground take out is secured under a nut to a ground stud on the left lower B-pillar (standard cab models) or the left lower cowl side inner panel (club cab and quad cab models). The seat belt switch is connected in series between ground and the seat belt switch sense input of the EMIC.