2009 GMC Sierra 1500 Crew Cab Owner's Manual - Page 120

Starting and Operating Your Vehicle New Vehicle Break-In Notice: The vehicle does not need an elaborate break-in. But it will perform better in the long run if you follow these guidelines: Ignition Positions The ignition switch has four different positions. • Keep your speed at 55 mph (88 km/h) or less for the first 500 miles (805 km). • Do not drive at any one constant speed, fast or slow, for the first 500 miles (805 km). Do not make full-throttle starts. Avoid downshifting to brake or slow the vehicle. • Avoid making hard stops for the first 200 miles (322 km) or so. During this time the new brake linings are not yet broken in. Hard stops with new linings can mean premature wear and earlier replacement. Follow this breaking-in guideline every time you get new brake linings. To shift out of P (Park), the ignition must be in ON/RUN or ACC/ACCESSORY and the regular brake pedal must be applied. A (LOCK/OFF): This position locks the ignition. It also locks the transmission on automatic transmission vehicles. The key can be removed in LOCK/OFF. On vehicles with an automatic transmission, the shift lever must be in P (Park) to turn the ignition switch to LOCK/OFF. • Do not tow a trailer during break-in. See Towing a Trailer on page 4-53 for the trailer towing capabilities of the vehicle and more information. Following break-in, engine speed and load can be gradually increased. 2-22