GM Service Manual Online
For 1990-2009 cars only

To wash your windshield, push in the button at the end of the stalk until the washers begin.

Caution: In freezing weather, do not use your washer until the windshield is warmed. Otherwise the washer fluid can form ice on the windshield, blocking your vision.

When you release the button, the washers will stop, but the wipers will continue to wipe for about three cycles and will either stop or will resume the speed you were using before.