Limp mode only when towing otherwise fine, HELP
OK folks need some help. Have owned a 2005 3500 Silverado dully for 3 years without problems. 163000 miles on the completely stock Duramax / Alison 1000 setup. The last month or so it has gone into limp mode but only when I start to tow our 5th wheel. It will reset if i pull over and turn it off for a min or two but I have only let this happen about 3 maybe 4 times. It will drive all day long and hundreds of miles at any speed without towing. All normal shifting, So I had the error codes pulled and get the classic P0700 from the ECM and so I know that means a internal trans error code and the local Alison shop will pull that code for me this coming Tue for $75 versus the Chevy dealers $100.
So here is my question, Is there anything that could possibly be wrong inside the trans like a solenoid or maybe the TCM needing to be re-flashed or replaced or something that could cause this without needing to do a complete rebuild? I just don't have the $ to do a complete rebuild right now, but something short of that , maybe. I don't mind spending the $75 if there's any chance they could find a cheap repair but if there's no chance at all short of rebuild and it's drive it for now without towing or rebuild I would rather not spend the $75 right now. THOUGHTS ?
Thanks for your suggestions
2005 Silverado 3500 DRW LB 4x4 LLY Duramax