GMC 2010 T-Series Owner's Manual page 57

Vehicles equipped with an Allison
transmission come with a push button shift selector that
will display transmission information. Refer to the
®
Allison Transmissions Operator's Manual for more
information on transmission diagnostics and shift
selector operation.
WARNING:
It can be dangerous to get out of the vehicle
without the parking brake firmly set. The vehicle
can roll. If you have left the engine running, the
vehicle can move suddenly. You or others could
be injured. To be sure the vehicle will not move,
even when you are on fairly level ground, always
set the parking brake.
®
3000 Series
WARNING:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is firmly on the brake pedal, the vehicle could
move very rapidly. You could lose control and hit
people or objects. Do not shift into a drive gear
while the engine is running at high speed.
Overdrive Defeat
If the vehicle has this feature, you can select to limit the
transmission to fourth gear. This may be useful when
operating at a higher Gross Vehicle Weight (GVW) or
where operating conditions do not require fifth gear.
The overdrive defeat
button is located in the
instrument panel to the
right of the steering
column. See Instrument
Panel Overview on
page 3 4 for more
information.
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