Brake System Warning Light - GMC 2007 Yukon Denali Owner's Manual

This condition is normal since the charging system
is not able to provide full power at engine idle.
As engine speeds are increased, this condition
should correct itself as higher engine speeds allow
the charging system to create maximum power.
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.
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Brake System Warning Light

With the ignition on, the brake system warning
light will come on when you set the parking brake.
If you try to drive with the parking brake engaged,
a chime will sound when the vehicle speed is
greater than 3 mph (5 km/h).
Your vehicle's hydraulic brake system is divided
into two parts. If one part is not working, the other
part can still work and stop you. For good
braking, though, you need both parts working well.
If the warning light comes on and a chime
sounds there could be a brake problem.
Have your brake system inspected right away.