GM Service Manual Online
For 1990-2009 cars only

When it is dark enough outside, the automatic headlamp system turns on the 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 be dim.

The vehicle has a light sensor on top of the instrument panel that controls the automatic headlamp system. Do not cover the sensor or the automatic headlamp system will turn on when it is not needed.

There is a delay in the transition between the daytime and nighttime operation of the 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 systems will only be affected when the light sensor sees a change in lighting lasting longer than this delay.

If vehicle is started in a dark garage, the automatic headlamp system comes on immediately. Once the vehicle leaves the garage, it takes about one minute for the automatic headlamp system to change to DRL if it is light outside. During that delay, the instrument panel cluster may not be as bright as usual. Make sure the instrument panel brightness control is in the full bright position. See Instrument Panel Brightness.

To idle the vehicle with the automatic headlamp system off, turn the ignition on and set the exterior light switch to the off/on position. For vehicles first sold in Canada, the transmission must stay in P (Park) for this function.

The regular headlamps should be used when needed.