Up-Shift Light (Manual Transmission); Brake System Warning Light - GMC 2005 Sierra 1500 Pickup Owner's Manual

Readings in the low warning zone may occur when a
large number of electrical accessories are operating in
the vehicle and the engine is left at an idle for an
extended period. 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.
Up-Shift Light (Manual
Transmission)
This light is used on some
models with manual
transmissions.
The shift indicator light will show you when to shift to
the next highest gear, and will help you get the best
fuel economy.

Brake System Warning Light

With the ignition on, the brake system warning light will
flash when you set the parking brake. The light will flash if
the parking brake doesn't release fully. 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 isn't working, the other part can still
work and stop you. For good braking, though, you
need both parts working well.
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