2010 GMC Yukon Owner's Manual - Page 20

Automatic Transmission Operation The vehicle has an electronic shift position indicator within the instrument panel cluster. There are several different positions for the shift lever. { WARNING: 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 in the Owner Manual. If you are pulling a trailer, see Towing a Trailer on page 5‑8. See "Range Selection Mode" later in this section. P (Park) : This position locks the rear wheels. It is the best position to use when you start the engine because the vehicle cannot move easily. When parked on a hill, especially when the vehicle has a heavy load, you may notice an increase in the effort to shift out of P (Park). See "Shifting Into P (Park)" in the Index of vehicle's owner manual for more information. 3-6