Chevrolet SUBURBAN 1993 Owner's Manual page 87

Features & Controls
Torque Lock
The parking brake should be set first whenever leaving the driver's seat. If
you are parked on a hill and the transmission
is placed in P (Park) before
the parking brake is set, the weight of the vehicle may put too much force
on
the parking pawl in the transmission. It may be difficult to pull the selector
lever out of P (Park). This is called "torque lock." To prevent this, the parking
brake should be set BEFORE moving the selector lever to P (Park).
When preparing to move the vehicle, the selector lever should be moved out
of
P (Park) BEFORE releasing the parking brake. Set the parking brake first,
then release the transmission from P (Park), even
on
level
surfaces.
If "torque lock" does occur, you may have to have another vehicle nudge
your vehicle uphill a little to take some of the pressure off the transmission
while you pull the selector lever out of P (Park).
Shifting lnto P (Park) (Automatic Transmission
Models
Only)
It can be dangerous to get out of your vehicle if the shift lever is not
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fully in P (Park) with the parking brake firmly set. Your vehicle can
roll.
If you have left the engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your vehicle won't move,
when you're on fairly level ground, use the steps that follow.
If you have four-wheel drive, and your transfer case is in N (Neutral),
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your vehicle will be free to roll-even if your shift lever is in P
(Park). So, be sure the transfer case is in a drive gear-not in N
(Neutral).
If you are parking on a hill, or if you're pulling a trailer, also see
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"Parking on Hills" or "Towing a Trailer" in the Index.
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