Seat Belt Switch - Operation

OPERATION

The seat belt switch is designed to control a path to ground for the seat belt switch sense input of the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN). The seat belt switch plunger is actuated by the seat belt webbing wound onto the seat belt retractor spool. When the seat belt tip-half webbing is pulled out of the retractor far enough to engage the seat belt buckle-half, the switch plunger is extended and closes the seat belt switch sense circuit to ground. Conversely, when the seat belt tip-half webbing is wound onto the retractor spool the switch plunger is depressed, opening the ground path.

The EMIC monitors the seat belt switch status, then controls the illumination of the seatbelt indicator and the generation of audible electronic chime tones based upon that input. The seat belt switch receives ground through its 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 ground screw. The seat belt switch is connected in series between ground and the seat belt switch sense input of the EMIC.

The seat belt switch as well as the hard wired inputs and outputs of the switch may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.