2003 GMC Sierra 1500 Pickup Owner's Manual - Page 311

Here are some things you must not do if you stall, or are about to stall, when going up a hill. Never attempt to prevent a stall by shifting into NEUTRAL (N) (or pressing the clutch, if you have a manual transmission) to 'rev-up' the engine and regain forward momentum. This won't work. Your vehicle will roll backwards very quickly and you could go out of control. Instead, apply the regular brake to stop the vehicle. Then apply the parking brake. Shift to REVERSE (R), release the parking brake, and slowly back straight down. Never attempt to turn around if you are about to stall when going up a hill. If the hill is steep enough to stall your vehicle, it's steep enough to cause you to roll over if you turn around. If you can't make it up the hill, you must back straight down the hill. Q: Suppose, after stalling,I try to back down the hill and decideI just can't do What should I do? it. A: Set the parking brake, put your transmission in PARK (P), or the manual transmission in FIRST ( l ) , 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. Shifting the transfer case to NEUTRAL can cause your vehicle to roll even if the transmission is in PARK (P) (or, if you have the manual transmission, even if you're in gear). This is because the NEUTRAL position on the transfer case overrides the transmission. You or someone else could be injured. If you are going toleave your vehicle, set the parking brake and shift the CAUTION: (Continued) 4-30