2006 GMC Yukon Owner's Manual - Page 170

Windshield Washer L(Washer Fluid): There is a paddle marked with the windshield washer symbol at the top of the multifunction lever. To spray washer fluid on the windshield, push the paddle. The wipers will clear the window and then either stop or return to your preset speed. This knob is located on the instrument panel to the left of the steering wheel. {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. To turn the rear wiper on, turn the knob to either 1 or 2. For long delayed wiping, turn the knob to 1. For short delayed wiping, turn the knob to 2. 9(Off): To turn the wiper off, turn the knob to this symbol. Rear Window Wiper/Washer =(Washer Fluid): To wash the window, press the knob with this symbol. The rear window washer uses the same fluid bottle as the windshield washer. However, the rear window washer will run out of fluid before the windshield washer. If you can wash your windshield but not your rear windows, check the fluid level. {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. 3-10