Navistar WorkStar Series, Operator'S Manual

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Operation
Both the T-Bar gearshift control and the Push-button gearshift
control are available with the Allison automatic transmissions.
They provide the same gear shift functions and control the
transmission in the same manner.
Allison Generation IV T-Bar Gearshift Control
1. Hold Override Button
2. Mode Indicator (Led)
3. Mode Button
4. Mode Id
5. Digital Display
6. Display Mode Diagnostic Button
When the vehicle is started, the transmissions are designed
to operate in the standard performance mode. Pressing the
Mode button on the shift tower will switch the transmission
to Economy mode and illuminate Mode ON in the shift tower
display. Economy mode provides operation at a lower engine
RPM while maintaining adequate performance.
If the engine speed is above idle when a gear is selected with the
shift tower, the vehicle will not move. To move the vehicle, the
shift tower must be moved to re-select a gear after the engine
comes down to idle.
For further information on the Allison transmission, refer to
the separate Allison vocational transmission model Operator’s
Manual.
Torque Lock
If the vehicle is parked on an incline and P (Park) is properly
engaged, the weight of the vehicle may generate an excessive
amount of torque on the park pawl in the transmission. In this
situation, it may be difficult to shift the transmission out of the
P (Park) position. To drive the vehicle out of the torque lock,
perform the following:
• Push the vehicle uphill a small amount to release the
pressure on the park pawl and permit the shift out of P
(Park). At this point, place foot on brake pedal.
• Hold foot on brake pedal while shifting the transmission out
of P (Park).
• Release the parking brake.
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