Range Inhibit Indicator, 2000 and 2400 Series

m2 dm 08.03.002

A RANGE INHIBIT indicator is a standard feature of the 2000 series and 2400 series transmissions. The RANGE INHIBIT indicator comes on to alert the driver that transmission operation is being inhibited and that the range shifts being requested by the driver may not occur. When certain operating conditions are detected by the TCM (transmission control module), the controls will lock the transmission in the current operating range.

Shift inhibits occur under the following conditions:

  • Shifts from neutral to reverse or from neutral to a forward range are not permitted when the engine is above idle (greater than 900 rpm).

  • Forward/reverse directional shifts are typically not permitted if appreciable output shaft speed is detected.

  • When some types of unusual transmission operating conditions are detected by the TCM, the TCM temporarily limits transmission operation until the vehicle can be driven to a service location. When this type of situation is detected, the TCM will lock the transmission in a safe gear range.

  • The TCM will prevent shifts from park or neutral to range when auxiliary equipment, such as a power takeoff unit (PTO), is in operation.

Note:
Parent topic: Allison On-Highway Transmissions
Document Number: 0000117761
Manual Publication Date: 2025-02-11
Topic Publication Date: 2024-05-09