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1, 2, D Gears. Occasionally, the road conditions, load, or traffic conditions will make
it desirable to restrict shifting to a higher gear. Positions "D", "2", and "1" provide pro-
gressively greater engine power and braking for going down grades (the lower the
gear, the greater the braking effect).
1 Gear. Use position "1" gear when pulling through mud and deep snow, when ma-
neuvering in tight spaces, or while driving up or down grades. Low gear provides the
vehicle with its maximum power and maximum engine braking power.
Park. If your bus is equipped with a "Park" selection, use it only after coming to a
complete stop, and then apply the parking brake. Do not rely upon the transmission
park pawl position alone to prevent the bus from rolling.
Range Inhibited Light
Under certain operating conditions, the Transmission Control Module (TCM) may de-
termine that it is necessary to restrict gear selection to protect the transmission from
damage and provide safer operating conditions. When this happens, the "RANGE
INHIBITED" warning light will activate, and the transmission may not respond to the
operator's commands. Please see the Range Inhibited Light and Shift Inhibits section
of the Allison Transmission operator's manual for more information.
Check Transmission Light
The "CHECK TRANSMISSION" light is located in the instrument panel. The electronic
control system is programmed to inform you if operating parameters have been ex-
ceeded and to automatically take action to protect the transmission. A diagnostic
code will be registered when the "CHECK TRANSMISSION" light is on.
When the engine is started, the "CHECK TRANSMISSION" light turns on for a few
seconds. This momentary indication shows that the lighting circuit is working prop-
erly.
If the light illuminates after startup, a problem has been detected. A diagnostic
code will be recorded and shifts may be restricted. Depending on the problem's se-
verity, the operator may continue driving to reach service assistance. The TCM may
restrict upshifts and downshifts. Please see your Allison Transmission operator's
manual for more details on how shifts may be inhibited.
ROUTINE OPERATION
[CAUTION] If the transmission
will not shift into "D" (drive), or
"R" (reverse), it may be because
of an adverse operating condition
such as; engine RPM too high or
service brakes not applied when
attempting to shift from neutral.
Check for the "RANGE INHIBITED"
message or "CHECK TRANS" light.
See the appropriate section of the
Allison transmission manual.
83
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