Automatic trans only shifts manually

[firedog11]

My 2002 Sport Trac with 4.0 automatic will only shift if I manually shift through. I start in 1, then manually shift to 2. I turn the OD off before shifting to D. Once I am up to speed, I can turn the OD on and it shifts. I changed the filter and pan fluid. I don't have a good transmission shop around to take it to. Could this be a valve issue, or is the transmission in need of a rebuild. Thanks in advance.

 

[410Fortune]

How many miles?

It’s likely time for a reman of your 5r55e

There are several things you can check but I’m not the guy to get you started on that there are several others here who know what to check first

I know the valve body gaskets leak
I know the bands get out of adjustment

You should check your computer for any transmission codes
You can also monitor live data as you drive and watch the pcm command shifts and how the trans responds

The 5r is actually a. 4 speed automatic and it uses 1st gear and overdrive (computer commanded) to create a “false” second gear

Usually when these units fail reverse or first gear go away first

 

[firedog11]

Thanks, 410Fortune. It s to has 313K, but I have no idea if that's correct or if everything is original. It has no CEL on as long as I shift that way. If I don't, then it sets codes P0731-P0734 & P0741.