Shifting Out Of Park (P); Torque Lock - GMC Envoy 2003 Owner's Manual

If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and your
parking brake is firmly set before you leave it. After
you've moved the shift lever into PARK (P), hold
the regular brake pedal down. Then, see if you can
move the shift lever away from PARK (P) without first
pressing the button on the console shift lever. If you can,
it means that the shift lever wasn't fully locked into
PARK (P).

Torque Lock

If you are parking on a hill and you don't shift your
transmission into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl
in the transmission. You may find it difficult to pull the
shift lever out of PARK (P). This is called "torque
lock." To prevent torque lock, set the parking brake and
then shift into PARK (P) properly before you leave
the driver's seat. To find out how, see Shifting Into
Park (P) on page 2-29 .
When you are ready to drive, move the shift lever out of
PARK (P) before you release the parking brake.
If torque lock does occur, you may need to have another
vehicle push yours a little uphill to take some of the
pressure from the parking pawl in the transmission, so
you can pull the shift lever out of PARK (P).

Shifting Out of Park (P)

Your vehicle has an automatic transmission shift lock
control system. You have to fully apply the regular
brakes before you can shift from PARK (P) when the
ignition is in RUN. See Automatic Transmission
Operation on page 2-23 .
2-31