Aisin downshift trouble

[Skram]

I have a 2014 3500 4x4 DRW, CC long box with 50,000 miles. Exhaust was deleted and EFI towing tune installed at 30,000 miles because of never ending trips to dealer with exhaust issues. I drive very conservatively. After about 5000 trouble free miles transmission developed a problem. Only happens when towing my 17,000 lb 5th wheel. Going up a steep hill trans downshifts from 6th to 5th and sometimes when it should shift to 4th it seems to delay. Engine lugs down to around 1200 rpm and then there is a loud bang and trans just feels like it jumps out of gear into neutral. You coast over to side of road and as you slow down it slams into 2nd gear .You can limp along like this. Shutting truck off and restarting takes it out of limp mode and it drives perfect again. Been into multiple dealers and had TCM flashed and updated but never fixed the problem. The valve body was suspected and changed but didn't fix the problem. Manually downshifting 5 to 4 happens smoothly and no issues. If you don't downshift in time though you get the loud bang and into limp mode you go. Happened occasionally for 15,000 miles and then one day while it was happening I felt some slippage in 5th so took it into Aamco. Had set a code for slippage 4 ,5 , 6. Trans was pulled and inspected and signs of minimal slippage found. I found a new transmission at a good price so went ahead and installed that with latest software in TCM. Trans shifts great, very smooth, and now has 1000 miles on it. Yesterday when going up a hill loaded, 6th to 5th, great, then slow to shift down to 4th and bang, I'm back in limp mode. New trans, same old problem. Anyone had this problem and any ideas on what is going on?

 

[Learjet]

I have a 2014 3500 4x4 DRW, CC long box with 50,000 miles. Exhaust was deleted and EFI towing tune installed at 30,000 miles because of never ending trips to dealer with exhaust issues. I drive very conservatively. After about 5000 trouble free miles transmission developed a problem. Only happens when towing my 17,000 lb 5th wheel. Going up a steep hill trans downshifts from 6th to 5th and sometimes when it should shift to 4th it seems to delay. Engine lugs down to around 1200 rpm and then there is a loud bang and trans just feels like it jumps out of gear into neutral. You coast over to side of road and as you slow down it slams into 2nd gear .You can limp along like this. Shutting truck off and restarting takes it out of limp mode and it drives perfect again. Been into multiple dealers and had TCM flashed and updated but never fixed the problem. The valve body was suspected and changed but didn't fix the problem. Manually downshifting 5 to 4 happens smoothly and no issues. If you don't downshift in time though you get the loud bang and into limp mode you go. Happened occasionally for 15,000 miles and then one day while it was happening I felt some slippage in 5th so took it into Aamco. Had set a code for slippage 4 ,5 , 6. Trans was pulled and inspected and signs of minimal slippage found. I found a new transmission at a good price so went ahead and installed that with latest software in TCM. Trans shifts great, very smooth, and now has 1000 miles on it. Yesterday when going up a hill loaded, 6th to 5th, great, then slow to shift down to 4th and bang, I'm back in limp mode. New trans, same old problem. Anyone had this problem and any ideas on what is going on?

you don't think your EFI tuning is messing with the transmission? I would think the TCM gets information from the ECM and the TCM sends info to the ECM...like when to defuel for shifting etc.?

 

[tp0d]

yep would contact EFI or whomever made the tune... sure aint the trans

 

[Skram]

Thank you both for the advice. I've contacted the company that installed the tune and they say there is no way it can influence the trans. I don't believe that now, so I'll contact EFILIVE directly.