2009 GMC Acadia Owner's Manual - Page 92

2-24 Features and Controls Automatic Transmission Operation The automatic transmission has a shift lever located on the console between the seats. { CAUTION It is dangerous to get out of the vehicle if the shift lever is not fully in P (Park) with the parking brake firmly set. The vehicle can roll. Do not leave the vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure the vehicle will not move, even when you are on fairly level ground, always set the parking brake and move the shift lever to P (Park). See Shifting Into Park on page 2-28. If you are pulling a trailer, see Towing a Trailer on page 4-24. Make sure the shift lever is fully in P (Park) before starting the engine. The vehicle has an automatic transmission shift lock control system. You must fully apply the regular brake first and then press the shift lever button before shifting from P (Park) when the ignition key is in ON/RUN. If you cannot shift out of P (Park), ease pressure on the shift lever, then push the shift lever all the way into P (Park) as you maintain brake application. Then press the shift lever button and move the shift lever into another gear. See Shifting Out of Park on page 2-29. R (Reverse): Use this gear to back up. Notice: Shifting to R (Reverse) while the vehicle is moving forward could damage the transmission. The repairs would not be covered by the vehicle warranty. Shift to R (Reverse) only after the vehicle is stopped. To rock the vehicle back and forth to get out of snow, ice or sand without damaging the transmission, see If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow on page 4-15. P (Park): This position locks the front wheels. It is the best position to use when starting the engine because the vehicle cannot move easily.