Automatic Headlamps and Parklamps

WARNING: This page is about a different car, the 2002 Pontiac Montana, 2002 Oldsmobile Silhouette, and 2002 Chevrolet Venture. However, it is still accessible from the selected car via links, so may be relevant.

The automatic headlamps and parklamps are designed to automatically illuminate when the ignition is RUN and the outside (ambient) light level is low, as in nighttime conditions. Light levels are detected by the ambient light sensor, a light sensitive transistor that varies its voltage signal to the daytime running lamp (DRL) control module in response to changes to the ambient light level. When the DRL control module receives a low light signal from the ambient light sensor, it will then turn on the headlamps and parklamps. The daytime running lamps will not operate when the automatic headlamps and parklamps are on.

When the ambient light sensor detects low light levels, the DRL control module turns OFF the daytime running lamps and turns on the headlamps and parklamps under the following conditions:

The ignition switch is in the RUN position.
The headlamp switch is OFF.
The park brake is OFF (released).

If the engine stalls with the DRL control module in the low light mode, the DRL control module turns OFF the headlamps while the engine is being cranked. The parklamps will remain ON while the engine is being cranked.