2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 396

. If the engine has stopped running, you need to restart it. With the brake pedal pressed and the parking brake still applied, shift the transmission to P (Park) and restart the engine. Then, shift to R (Reverse), release the parking brake, and slowly back down the hill as straight as possible in R (Reverse). While backing down the hill, put your left hand on the steering wheel at the 12 o'clock position so you can tell if the wheels are straight and can maneuver as you back down. It is best to back down the hill with the wheels straight rather than in the left or right direction. Turning the wheel too far to the left or right will increase the possibility of a rollover. If, after stalling, you try to back down the hill and decide you just cannot do it, set the parking brake, put your transmission in P (Park), and turn off the engine. Leave the vehicle and go get some help. Exit on the uphill side and stay clear of the path the vehicle would take if it rolled downhill. Do not shift the transfer case to Neutral when you leave the vehicle. Leave it in some gear. . { WARNING: Shifting the transfer case to Neutral can cause your vehicle to roll even if the transmission is in P (Park). This is because the Neutral position on the transfer case overrides the transmission. You or someone else could be injured. If you are going to leave your vehicle, set the parking brake and shift the transmission to P (Park). But do not shift the transfer case to Neutral. Things not to do if the vehicle stalls, or is about to stall, when going up a hill: . Never attempt to prevent a stall by shifting into N (Neutral) to rev-up the engine and regain forward momentum. This will not work. The vehicle can roll backward very quickly and could go out of control. Never try to turn around if about to stall when going up a hill. If the hill is steep enough to stall the vehicle, it is steep enough to cause it to roll over. If you cannot make it up the hill, back straight down the hill. . 5-20