Left Multi-Function Switch: Operation: Notes

The left (lighting) multi-function switch uses resistor multiplexing to control the many functions and features it provides using a minimal number of hard wired circuits. The switch receives clean grounds from the Steering Control Module (SCM), then provides resistor multiplexed return outputs to the SCM to indicate the selected switch positions. The SCM then sends electronic switch status messages over the Controller Area Network (CAN) data bus to the other electronic modules in the vehicle.

If the SCM detects no inputs from the left multi-function switch, it transmits a Signal Not Available (SNA) status over the CAN data bus. The SNA status signals the other electronic modules to implement a failsafe mode of operation for the exterior lighting system. The failsafe mode automatically turns the exterior lighting On when the ignition switch is in the On position, and Off when the ignition switch is in the Off position.

The left multi-function switch can be diagnosed using conventional diagnostic tools and methods. However, the most reliable, efficient and accurate means to diagnose this component requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.