Hazard Warning Switch - Operation

OPERATION

The status of the hazard switch in the upper instrument panel switch pod is continually monitored by the Body Control Module (BCM) through a hard wired hazard switch sense circuit. When the BCM detects the switch has closed, it controls hazard warning system operation and flash rate by toggling a control output that energizes and de-energizes the relays in the Power Distribution Center (PDC) that provide battery current to the lamps in the right and left turn signal circuits.

The BCM also sends the appropriate electronic messages back to the Instrument Panel Cluster (IPC) to control the illumination and flash rate of the right and left turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the IPC electronic circuit board that emulates the sound emitted by a conventional hazard warning flasher.

The hard wired circuits for the upper 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 system 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 warning system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.