A friend of mine bought a 03 chevy 2500 with the duramax engine/ allison trans in it. While at full throttle in any gear it will not shift into the next gear without letting off. It's been back to the dealer he got it from twice now and they claim its alright. Anybody got any ideas what could causing this????? Also as far as I know nothing has been done to it but he's not the original owner so who knows...

 

its not a trans issue.

engine fuel pressure related limp. First have him change the fuel filter, then if it continues to do it, have him get the touble codes read.

 

i heard a issue with d-max if they are plugged in above 0 degrees it messed up the computer, and tranny shifts. the had a service bullitin on it and now have a thermostat in the plug itself

 

Thanks, i'll let him know. I guess i'll be changing out a filter tomorrow (somehow I seem to be his mechanic). Sure hope thats the problem. Ken

 

I'll check into that for him too.

 

plugging in above 0* will only throw a check engine light on the LLY's and LBZ'.

But even the check engien light o the LLY and LBZ's wont make the trans shift funny.

Its not something the trans is doing. Its the engine. Its giving it a 2000 rpm limit, so if you floor the pedal, the trans wont shift because its waitin to see WOT (3200rpm) before it will shift.

 

Thanks that fixed it.