Voltmeter Gage; Service Transmission Warning Light - GMC 2005 T-Series Owner's Manual

Voltmeter Gage

Readings in either warning zone indicate a possible
problem in the electrical system.
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 may not be able to provide full power
at engine idle. As engine speeds are increased, this
condition should correct itself because higher engine
speeds allow the charging system to create
maximum power.
You can only drive a short time on the battery. Be sure
to shut off the radio, the fan or any unnecessary
accessories and have the system serviced.
3-26
When your engine is
running, the voltmeter
gage shows the charging
system voltage.

Service Transmission Warning Light

If your vehicle has an Allison automatic transmission,
certain transmission malfunctions will turn this light on.
If this light comes on while you are driving, do not use
the transmission shift control or you may lose forward
gears. The computer for the transmission senses
a problem and chooses a gear to stay in so that you
can drive the vehicle in that gear. You may not be able
to drive as fast or back up when this light is on.
Notice: If you continue driving your vehicle after the
transmission warning light comes on, you could
damage the transmission. While this light is on, the
transmission cannot operate in all gears. If you
attempt to shift gears, the vehicle may not continue
to move. Do not attempt to shift gears while the
transmission warning light is on. Instead, drive
directly to a GM dealer for service. If you cannot drive
to a dealer immediately, have the vehicle towed.
This light is located with
the auxiliary warning lights
in the center of the
instrument panel.