Seat Belt Switch - Operation

OPERATION

DRIVER SIDE

The driver front seat belt switch is designed to control a path to ground for the seat belt switch sense input of the Totally Integrated Power Module (TIPM). When the driver front seat belt tip-half is inserted into the seat belt buckle, the switch closes the path to ground; and, when the driver side front seat belt tip-half is removed from the seat belt buckle, the switch opens the ground path. The switch is actuated by the latch mechanism within the seat belt buckle. The TIPM provides electronic driver seat belt switch status messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Controller Area Network (CAN) data bus. The EMIC uses these messages as an additional logic input for control of the seat belt indicator.

The driver side front seat belt switch is connected in series between ground and the seat belt switch sense input of the TIPM. The seat belt switch receives ground at all times through its pigtail wire connection to the driver seat wire harness from a take out of the body wire harness that is secured to the body sheet metal. The TIPM monitors the condition of the driver seat belt switch circuits and will send an electronic message to illuminate the airbag indicator in the EMIC, then store a Diagnostic Trouble Code (DTC) for any fault that is detected.

The hard wired circuits between the driver seat belt switch and the TIPM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the switch or the electronic controls or communication between other modules and devices that provide some features of the seat belt reminder system. The most reliable, efficient, and accurate means to diagnose the driver seat belt switch or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

PASSENGER SIDE

The passenger front seat belt switch is designed to control a hard wired sense input to the Occupant Restraint Controller (ORC). When the passenger front seat belt tip-half is inserted into the seat belt buckle, the switch closes the passenger seat belt switch sense circuit; and, when the passenger front seat belt tip-half is removed from the seat belt buckle, the switch opens the circuit. The switch is actuated by the latch mechanism within the seat belt buckle. The ORC provides electronic passenger seat belt switch status messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Controller Area Network (CAN) data bus. The EMIC uses these messages as an additional logic input for control of the seat belt indicator.

The passenger front seat belt switch is connected in series between the passenger seat belt switch plus (+) and minus (-) circuits of the ORC through its pigtail wire connection to the passenger seat wire harness. The ORC also monitors the condition of the seat belt switch circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected.

The hard wired circuits between the passenger seat belt switch and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the switch or the electronic controls or communication between other modules and devices that provide some features of the seat belt reminder system. The most reliable, efficient, and accurate means to diagnose the passenger seat belt switch or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.