2003 GMC Sierra 1500 Pickup Owner's Manual - Page 304

3. Pull the push-pins and lower da.m assembly away from the retainers until the lower dam is free. To reinstall the lowerairdam, do the following: 1. Line up each push-pin with its intended retainer and push the washer portion of the push-pin toward the retainer until it locks into place. When you're back on roads, though, be sure to replace the air dam. Notice: Operating your vehicle for extended periods without the front bumper lower air dam installed can cause improper air flow to the engine and may allow things like fog lamps or tow hooks on the front of your vehicle to be damaged. Always be sure to replace the front bumper air dam when you're finished off-road driving. 2. Push the flat end of the push-pin toward the retainer until it locks into place, making sure each is secure. 4-23