Chevrolet B7 2001 Owner's Manual page 30

If your vehicle has air brakes, the parking brake control
will be located on the instrument panel to the right of the
steering column.
If the air pressure drops below 60 to 70 psi (413 to
482 kPa), the LOW AIR light will come on. If the air
pressure drops to 40 to 45 psi (275 to 309 kPa), the
yellow knob will automatically pop out and apply the
spring brakes. If you ever have a complete loss of air,
so that your air brakes automatically apply, there is a
way that the tow operator can release the parking brakes
to tow the vehicle. See "Towing Your Vehicle" in
the Index.
To apply the parking brake,
pull this knob toward you.
To release the parking
brake, push the knob in.
CAUTION:
If your vehicle is left in gear, the engine can
start if the vehicle starts to roll. This can easily
happen if you have the diesel engine. Shift the
transmission into NEUTRAL (N) before you
leave the vehicle.
Parking Over Things That Burn
CAUTION:
Things that can burn could touch hot exhaust
parts under your vehicle and ignite. Don't park
over papers, leaves, dry grass or other things that
can burn.
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