Incorrect gear ratio on reverse 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 reverse gear ratio does not agree with the calculated reverse 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 reverse gear.
Possible cause
It is probably a mechanical problem which causes this, for example, a problem with clutches C3 and C5 for reverse gear.