My Allison Tranny will not shift forward or reverse! Started with not shifting out of gear at speed, then went to nonoperational at all! Can't drive, dead in the water! Automatic. Was running great last night at 75 on the highway. My baby is my 2011 GMC Denali HD2500 with the 6.6 Duramax and Allison Tranny. Nothing better! But, just stopped!! Tranny fluid is full? Not one dummy light on? All pressure gauges look good? 138k miles.
My Allison Tranny will not shift forward or reverse! Started with not shifting out of gear at speed, then went to nonoperational at all! Can't drive, dead in the water! Automatic. Was running great last night at 75 on the highway. My baby is my 2011 GMC Denali HD2500 with the 6.6 Duramax and Allison Tranny. Nothing better! But, just stopped!! Tranny fluid is full? Not one dummy light on? All pressure gauges look good? 138k miles.
- gmcmandenali1999, Laporte, US