GM Service Manual Online
For 1990-2009 cars only

This feature automatically turns on the headlamps and parking lamps if the exterior lamp control is set in the AUTO position and the windshield wipers are turned on and have completed eight wipe cycles. See Exterior Lamps for additional information.

When the ignition is turned off, the wiper-activated headlamps immediately turn off. They also turn off if the windshield wiper control is turned off.