GM Service Manual Online
For 1990-2009 cars only

When it is dark enough outside, your automatic headlamp system will turn on your headlamps at the normal brightness along with other lamps such as the taillamps, sidemarker, parking lamps and the instrument panel lights. The radio lights will also dim.

Your vehicle is equipped with a light sensor on the top of the instrument panel in the defroster grille. Be sure it is not covered, or the system will be on whenever the ignition is on.

The system may also turn on your headlamps when driving through a parking garage, heavy overcast weather or a tunnel. This is normal.

There is a delay in the transition between the daytime and nighttime operation of the Daytime Running Lamps (DRL) and the automatic headlamp systems so that driving under bridges or bright overhead street lights does not affect the system. The DRL and automatic headlamp system will only be affected when the light sensor sees a change in lighting lasting longer than the delay.

To idle your vehicle with the automatic headlamp system off, set the parking brake while the ignition is off. Then start your vehicle. The automatic headlamp system will stay off until you release the parking brake.

You may be able to turn off your automatic headlamp system. See Daytime Running Lamps (DRL) for more information.

As with any vehicle, you should turn on the regular headlamps when you need them.