Operation

OPERATION

The status of the hazard switch is continually monitored by the circuitry within the instrument panel switch pod (also known as the center console switch unit, Switch Bank Module/SBM, Upper Control Panel/UCP or OBF). The switch pod receives battery voltage at all times on a fused battery feed circuit, and a path to ground at all times through the vehicle wire harness. The only other inputs to the switch pod consist of electronic communication with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus.

Whenever the hazard switch is activated or deactivated the switch pod circuitry sends electronic hazard switch status messages over the CAN data bus. When the Body Control Module (BCM) (also known as the Signal Acquisition and Actuation Module/SAM) receives a hazard switch status input it then controls hazard warning system operation and flash rate by controlling battery voltage outputs through high side drivers on the right and left turn signal feed circuits. The BCM then sends messages back to the switch pod to control the illumination of the hazard switch push button Light Emitting Diode (LED) indicator.

The hard wired circuits for the instrument panel switch pod 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 hazard warning switch or the electronic controls and communication between other modules and devices that provide some features of the hazard warning system. The most reliable, efficient, and accurate means to diagnose the hazard switch or the electronic controls and communication related to hazard switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.