Supply voltage too high from actuator 1
â–¶ How to fix
Check the control unit cable harness. Contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
The Allison fault code number is: P0659.All solenoids are shut off. The gear selector position and the hydraulic position of the solenoids determine which gear is activated in the gearbox.
Diagnostic depth
Detection
Supply voltage for actuator 1 (HSD1) is too high.
Possible cause
The control unit has detected 6 V or more in actuator 1 (HSD1) circuit after two solenoids have indicated a fault. This can be caused by a short circuit to battery in the actuator 1 circuit.