GMC 1995 Safari Owner's Manual page 312

Steering Column Lock
While parked, and with the parking brake set, try to turn the key to LOCK
in each shift lever position.
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The key should turn to LOCK only when the shift lever is in PARK
(P).
The key should come out only in LOCK.
Parking Brake and Automatic Transmission PARK (P)
Mechanism Check
Park on a fairly steep hill, with the vehicle facing downhill. Keeping your
foot on the regular brake, set the parking brake.
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To check the parking brake: With the engine running and transmission
in NEUTRAL (N), slowly remove foot pressure from the regular brake
pedal. Do this until the vehicle is held by the parking brake only.
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To check the PARK (P) mechanism's holding ability: Shift to PARK
(P). Then release all brakes.
Lap and Shoulder Belts Condition and Operation
Inspect belt system, including: webbing, buckles, latch plates, retractors,
guide loops and anchors. Have a belt assembly replaced if the webbing has
been cut or otherwise damaged.
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