2008 GMC Sierra 1500 Pickup Owner's Manual - Page 439

Automatic Transmission Shift Lock Control System Check Ignition Transmission Lock Check While parked, and with the parking brake set, try to turn the ignition to LOCK/OFF in each shift lever position. {CAUTION: When you are doing this inspection, the vehicle could move suddenly. If the vehicle moves, you or others could be injured. 1. Before you start, be sure you have enough room around the vehicle. It should be parked on a level surface. 2. Firmly apply the parking brake. See Parking Brake on page 2-32. Be ready to apply the regular brake immediately if the vehicle begins to move. 3. With the engine off, turn the ignition to ON/RUN, but do not start the engine. Without applying the regular brake, try to move the shift lever out of PARK (P) with normal effort. If the shift lever moves out of PARK (P), contact your dealer/retailer for service. • The ignition should turn to LOCK/OFF only when the shift lever is in PARK (P). • The ignition key should come out only in LOCK/OFF. Contact your dealer/retailer if service is required. Parking Brake and Automatic Transmission Park (P) Mechanism Check {CAUTION: When you are doing this check, your vehicle could begin to move. You or others could be injured and property could be damaged. Make sure there is room in front of your vehicle in case it begins to roll. Be ready to apply the regular brake at once should the vehicle begin to move. Park on a fairly steep hill, with the vehicle facing downhill. Keeping your foot on the regular brake, set the parking brake. 6-11