Short circuit in the engine speed sensor.
Check the cable harness and renew the rotational speed sensor.Contact an Allison dealer if the fault persists.The fault code can be cleared manually using SDP3 or using Allison's diagnostic tool. The fault code is cleared automatically, when the vehicle has completed 40 start-up cycles without the fault being detected again.
What you'll see
No driver-visible symptom recorded.
System reaction
The fault code is stored in the memory.The control unit sets the engine speed to the same as turbine rotational speed.
Diagnostic depth
The control unit has detected a short circuit in the engine speed sensor.
Possible causes:Damaged cable harness.Defective rotational speed sensor.There are changes of a minimum of 1,040 rpm in engine speed.The rotational speed of the shaft is less than 61 rpm for more than 4 seconds.The check is activated in the calibration. For the low engine speed test, the turbine rotational speed must be above 400 rpm and 15 voltage must be switched on.