General Information, Allison
Refer to the Allison website for additional information,www.allisontransmission.com .
HD-series automatic transmissions have six forward speeds and one reverse speed. See Fig.. These transmissions have electronic shift controls that can be programmed to allow the use of different numbers of geared speeds. For instance, the transmission can be programmed to operate as a 4-speed, 5-speed, or 6-speed unit in the "primary" shift mode. If needed, a "secondary" shift mode can be programmed to provide another shift configuration to optimize vehicle use under different operating conditions. To activate a secondary shift mode, or other special function programmed into the electronic control unit (ECU), depress the Mode button. "Mode On" is displayed in the indicator panel just above the push buttons. A label just above the Mode button identifies the special function.
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9-Speed Shift Pattern with LO Gear
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9-Speed Shift Pattern
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10-Speed Shift Pattern
Fig. 1, Meritor ESS 9- and 10-Speed Shift Patterns
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Indicator Panel
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Mode ID
Fig. 2, Allison Push Button Shift Selector
Note: Each time a push button is depressed on the shift selector, a short beep will be heard. This indicates that the ECU has received input to change operation.
The HD-series transmission system is designed to warn the driver of transmission malfunctions. The driver of a vehicle equipped with these transmissions should know the extent of the warning system in order to safely operate the vehicle. See General Information for information on the warning system.