GMC C series 2002 Owner's Manual page 71

Lever Operated Parking Brake
The vehicle must be stopped when applying the parking
brake, except while burnishing the parking brake linings
(see "Propshaft Brake Burnish Procedure" in the Index).
You can easily adjust the parking brake by turning the
knob on the lever. Turning it clockwise makes the brake
grip more tightly. It will also make the lever seem harder
to pull up. Turning the knob counterclockwise makes the
parking brake apply less firmly. Adjust the parking
brake only when the lever is down (released).
If your parking brake doesn't hold the vehicle when
applied, see your GM Truck dealer who can adjust
your parking brake properly.
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To apply the parking brake,
pull the lever all the way up.
The PARK BRAKE light
will come on when the
parking brake is applied.
Then shift the transmission
to neutral or PARK (P).
The PARK BRAKE light will remain illuminated if the
parking brake is not fully released.
NOTICE:
Driving with the parking brake on can overheat
the parts in the system. You may have to replace
them, and you could also damage other parts of
your vehicle.
To release the parking
brake, first push down the
regular brake pedal. Then,
push the parking brake lever
all the way down and shift
the automatic transmission
to NEUTRAL (N).