Allison WTEC II Fault Code: 25 PID: SPN: 11 FMI: Output speed sensor, detected at 0 output rpm, 1st

Main code 25 occurs if the output speed sensor reports a zero speed reading while both engine and turbine speeds are approximately equal, turbine speed is above a calibration value, and neutral is not selected or commanded.

Possible Causes:
1. Output speed sensor has failed
2. The required oncoming clutch or clutches did not come on.

Code 25 11 can be generated by a false turbine speed reading. This may be due to crosstalk between solenoid and turbine speed sensor circuits caused by direct wire-to-wire short or by water in the electrical connectors.