Cadillac CTS 2008 Owner's Manual page 124

Leaving Your Vehicle With the Engine
Running (Automatic Transmission)
CAUTION:
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It can be dangerous to leave the vehicle with
the engine running. The vehicle could move
suddenly if the shift lever is not fully in
P (Park) with the parking brake firmly set.
And, if you leave the vehicle with the engine
running, it could overheat and even catch fire.
You or others could be injured. Do not leave
the vehicle with the engine running.
If you have to leave your automatic transmission
vehicle with the engine running, be sure your vehicle
is in P (Park) and your parking brake is firmly set before
you leave it. After you have moved the shift lever into
P (Park), hold the regular brake pedal down. Then, see if
you can move the shift lever away from P (Park) without
first pushing the button.
If you can, it means that the shift lever was not fully
locked into P (Park).
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Torque Lock (Automatic Transmission)
If you are parking on a hill and you do not shift the
automatic transmission into P (Park) 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 P (Park). This is called torque lock. To
prevent torque lock, set the parking brake and then shift
into P (Park) properly before you leave the driver's seat.
To find out how, see "Shifting Into P (Park)" previously in
the section.
When you are ready to drive, move the shift lever out of
P (Park) before releasing 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 P (Park).