Where can we get these transmission software update? on 2005 Chrysler Town & Country

I have a '05 T&C at 144,000 miles. Sometimes when we get it up to 3500 RPM's it will not shift (just stutters). My check engine light is on but the code reader that we have does not show any codes. We've changed the transmission fluid and filter and there's no changes.

Asked by for the 2005 Chrysler Town & Country
Better code readers or full flegged scanners can read Transmmision and Body codes. Its a matter of taking it to shop that has invested in the equipment to do the diagnosis you require.
1 more answer
best to take all tranny issues to tranny specialty shop. general auto motive shops are not usually equipped for tranny testing or repair(neither are the dealerships for that matter).