Allison WTEC II Fault Code: 53 PID: SPN: 38 FMI: Offgoing speed test (during shift), 3 to N1

Main code 53 indicates a failed offgoing speed test. 3?N1 shift

The speed test during a shift is designed to ensure neutral is attained during shifts to neutral. This test compares engine speed to turbine speed. If neutral is selected and turbine speed is found to be much lower than engine speed, the ECU sees this as neutral not being attained. The transmission is commanded to Neutral with No Clutches and Code 53 XX is set. Additional codes could be logged for other shifts where ?X? indicates the range from and ?Y? indicates the range to.