Incorrect gear ratio on 1st gear
â–¶ How to fix
Contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
Detection
Actual 1st gear ratio does not agree with the calculated 1st gear ratio. Gear ratio is determined on the basis of turbine speed and output shaft speed. This measured gear ratio is compared with what the gear ratio should be for 1st gear.
Possible cause
This is probably caused by a mechanical problem, for example a problem with C1 and C5 for 1st gear.