Just a note of what solved my trans codes
6 months ago had to get towed home for Allison Transmission codes:
D1 4416
D2 4621
D3 4627
It started with limiting to gear 5 from 7 and very hard shifting from 2nd to 3rd. After clearing and much consternation on a trip, I got it towed as when shiut off it then defaulted to DNS. I spent a lot of time learning about the transmission over winter as I prepared to hunt a likely grounded wire or the wire carrying the TransID (195) to ECM, which seems to be the culprit in many cases. Rarely was I told it was a real transmission issue.
Long story short, I started the spring project of getting it on the road and thought I would start with fresh batteries.
Believe it or not, the transcodes cleared, and trans now shifts and is no longer in a DNS state. I fired it up over winter a few times on jumper box but not on actual new batteries.
The manual talks about failure modes in low voltage conditions with gradual failure of solenoids in the above mentioned pattern. Thought I would write up the fix in case it helps others. REPLACE your batteries for good battery voltage before you condemn your transmission or ECM's as the culprit.
JP
6 months ago had to get towed home for Allison Transmission codes:
D1 4416
D2 4621
D3 4627
It started with limiting to gear 5 from 7 and very hard shifting from 2nd to 3rd. After clearing and much consternation on a trip, I got it towed as when shiut off it then defaulted to DNS. I spent a lot of time learning about the transmission over winter as I prepared to hunt a likely grounded wire or the wire carrying the TransID (195) to ECM, which seems to be the culprit in many cases. Rarely was I told it was a real transmission issue.
Long story short, I started the spring project of getting it on the road and thought I would start with fresh batteries.
Believe it or not, the transcodes cleared, and trans now shifts and is no longer in a DNS state. I fired it up over winter a few times on jumper box but not on actual new batteries.
The manual talks about failure modes in low voltage conditions with gradual failure of solenoids in the above mentioned pattern. Thought I would write up the fix in case it helps others. REPLACE your batteries for good battery voltage before you condemn your transmission or ECM's as the culprit.
JP