GMC 1999 Envoy Owner's Manual page 86

Pull the BRAKE RELEASE lever fully. It is located on
the bottom of the driver's side of the instrument panel.
NOTICE:
Driving with the parking brake on can cause
your rear brakes to overheat. You may have to
replace them, and you could also damage other
parts of your vehicle.
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If you are towing a trailer and you must park on a hill,
see "Towing a Trailer" in the Index. That section shows
what to do first to keep the trailer from moving.
Shifting Into PARK (P)
CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) 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, even when
you're on fairly level ground, use the steps that
follow. Always put the shift lever fully in
PARK (P) with the parking brake firmly set. If
you're pulling a trailer, see "Towing a Trailer" in
the Index.
1. Hold the brake pedal down with your right foot and
set the parking brake.
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