I am still trying to trouble shoot a downshift problem on a 4R70w transmission.

I get a hard downshift @ 40-70 (Above 70 it does not need to) when lightly accelerating. All other shifts are very smooth (Including when you step on it hard and hit what years ago was called the kick-down gear). No trouble code in the PCM.

What I am hunting for is a schematic for the 4R70w transmission that shows the different operations. I have tried to doing an internet search without luck. Does anybody know where I can get one?

 

Have you tried changing the tranny fluid?

 

The fluid and filter were changed about 500 miles ago.

As it only does it on one particular shift, to me, it feels like either a solenoid valve or servo is getting weak.

I am trying to track down all the solenoid valve and servos and what each one controls.

Any help would be greatly appreciated!!!