PCS Main modulation solenoid, short circuit to earth (U31)
â–¶ How to fix
Check the cable harness between gearbox and control unit. If no fault is found, contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
Detection
The control unit has detected a short circuit to earth on the return circuit for the main modulation solenoid.
Possible cause
A possible cause of this fault code is a damaged cable harness in the solenoid return circuit.