Operation

OPERATION

DRIVER SIDE

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 hard wired circuits between the driver side 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 features of the supplemental restraint system. The most reliable, efficient, and accurate means to diagnose the driver side 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

NOTE: If the passenger side seat belt switch is found to be causing a fault the entire buckle assembly must be replaced. Fault determination can be achieved using a scan tool and the proper DTC diagnostics.

The passenger side front seat belt switch is a hard wired input to the Occupant Restraint Controller (ORC). A spring-loaded slide with a small window-like opening is integral to the buckle latch mechanism. When a seat belt tip-half is inserted and latched into the seat belt buckle then the switch is engaged causing the Hall Effect Switch to send a higher voltage to the ORC. The reverse would be true when the latch is disengaged.

The passenger side seat belt switch receives a ground from the ORC through a hard wired connection, and the ORC senses the status of the seat belt buckle by monitoring the modulation of voltage through its connection to the seat belt switch output. The ORC provides electronic passenger side 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 controls the seat belt indicator based upon these electronic passenger side seat belt switch status message inputs. The ORC also monitors the condition of the passenger side seat belt switch circuits and will send an electronic message to illuminate the airbag indicator in the EMIC, then store a DTC for any fault that is detected.

The hard wired circuits between the passenger side seat belt switch and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. If the passenger side seat belt switch is found to be causing a fault the entire buckle assembly must be replaced. Fault determination can be achieved using a scan tool and the proper DTC diagnostics.