Control unit supply voltage (U30) too low
â–¶ How to fix
Check the battery and associated cable harness. Ensure that the cable harness between gearbox and control unit is not damaged. 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 supply voltage has been lower than a specific value.
Possible cause
The cause of this fault code may be: Fault on the vehicle battery.Corroded battery cables.Loose contact or damaged cable harness.