Fog Lamp Switch - Operation

OPERATION

The status of the fog lamp switch in the lower instrument panel switch pod is continually monitored by the Body Control Module (BCM) through a hard wired fog lamp switch sense circuit. When the BCM detects the switch has closed, it controls fog lamp system operation by toggling a control output that energizes and de-energizes the appropriate front or rear fog lamp relay in the Power Distribution Center (PDC) that provides battery current to the fog lamps.

One fog lamp switch button push turns the front fog lamps ON and the second push turns them OFF. For vehicles manufactured for sale in markets where rear fog lamps are required, the second button push turns the rear fog lamps ON, while a third button push turns both the front and rear fog lamps OFF. The BCM also sends the appropriate electronic messages back to the Instrument Panel Cluster (IPC) to control the illumination of the front and rear fog lamp indicators.

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