Circuit Description
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) monitors the park lamp switch signal circuit and the headlamp switch headlamps on signal circuit in order to determine when the park lamps and headlamps should be illuminated. When the headlamp switch is turned to PARK, the BCM senses that the park lamp switch signal circuit is grounded and the headlamps switch headlamps on signal circuit is open. The BCM will then energize the park lamp relay illuminating the parklamps. When the headlamp switch is turned to HEAD, the BCM senses that the park lamp switch signal circuit and the headlamp switch headlamps on signal circuit are grounded. The BCM will then energize the park lamp relay and headlamp driver module (HDM) illuminating the park lamps and headlamps.