GMC YUKON DENALI 2000 Manual page 147

You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.
Brake System Warning Light
The light will stay on if your parking brake doesn't
release fully. If it stays on after your parking brake is
fully released, it means you have a brake problem.
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though, you
need both parts working well.
When the ignition is on, the
brake system warning light
will come on when you set
your parking brake.
If the warning light comes on, there could be a brake
problem. Have your brake system inspected right away.
This light should come on briefly when you turn the
ignition key to RUN. If it doesn't come on then,
have it fixed so it will be ready to warn you if there's
a problem.
If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal is
harder to push. Or, the pedal may go closer to the floor.
It may take longer to stop. If the light is still on, have the
vehicle towed for service. (See "Towing Your Vehicle"
in the Index.)
CAUTION:
Your brake system may not be working properly
if the brake system warning light is on. Driving
with the brake system warning light on can lead
to an accident. If the light is still on after you've
pulled off the road and stopped carefully, have
the vehicle towed for service.
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