Disconnecting the battery will NOT reset the transmission control module. The TCM has non-volatile memory. The only way to reset it is with a DRBIII scan tool. I'd suggest you take it into a shop and have them perform a quick-learn reset.

It may get better after driving several hundred to a couple thousand miles as the TCM slowly relearns/adapts to the new fluid, but a reset will get it done much faster.

 

Sorry that I didn't mention that. It's with the fluid warmed up, truck in neutral and running. I've ran the transmission fluid at that level since 90k miles ..... and I'm at 131k now and not one issue with the higher level.

 

thanks B OH B

 

No problem!

 

Regnath, which tranny do you have? The 545RFE or the 42RLE? Do both have the over-fill bleed off valve?

 

I have the 545RFE. All transmissions should have a bleed off valve to prevent pressure from building as the transmission warms up and the fluid expands.

 

Update - I added fluid to over the full line, and still had rough downshifts. I've been slowly removing fluid trying to find the sweet spot. I don't have many opportunities to adjust fluid levels as the transmission does not fully warm up on the short drive to/from work so it has taken a few weeks to get this far.

I still don't understand why the issue only occurs with downshifts...