Circuit/System Description

The rear fog lamp switch is an input to the body control module (BCM) and is contained in the headlamp switch assembly. The BCM supplies voltage to the rear fog lamp switch via the rear fog lamp and instrument panel dimmer switch B+ circuit. When the rear fog lamp switch is pressed, voltage from the B+ circuit is pulled down through the rear fog lamp switch resistor. The rear fog lamp resistor is part of the resistor ladder that also provides the dimming signals for the instrument panel dimmer switches. The BCM receives the voltage signal through the rear fog lamp and instrument panel dimmer switch signal circuit.

The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch. The body control module (BCM) responds by applying voltage to the rear fog lamp control circuit which illuminates the rear fog lamp.