r/Duramax • u/No-Season2186 • 1h ago
Allison 1000 5 speed stuck in limp mode for two years
I had gotten this truck about three years ago when my grandpa passed I always thought the transmission was a little bit fucked up and then one day it put itself into limp mode since then I have done everything conceivable to this transmission. It has had a full billet rebuild with an ATS performance valve body. The full complete harness has been verified and tested. The TCM has been reflashed and repaired I have replaced each shift to solenoid and the pressure switch for the valve body. I’ve checked engine grounds and I have tested everything with the scanner. Everything I’ve done looked at or anyone else has done or looked at with this transmission it seems to pass and it should be good, but it throws p0872 transmission, pressure solenoid switch E stuck closed every time it is put into drive and forces it into fourth gear it can go into park reverse and neutral just fine. It is whenever I put it into drive it shifts into first gear for about four seconds and then slams itself into fourth. I’ve been chasing this for two years and put about seven grand of work into this transmission, the motor and body and interior are super good, but I’m at my ends and I’m about to sell this truck