4R55E Question..
 

So I have a '96 Explorer Limited, 4.0 with the 4r55e. It has a hair over 160k on it.

Here is my question, I thought the valve body gaskets where blown because it would have pretty hard up and down shifts SOMETIMES. It's very random, some day's it would do it.. Others it wouldn't. Then I was reading if it has engine braking in manual 1st gear.. The gasket's are ok. I'm pretty sure I've used manual 1st before and felt engine braking. Will check tomorrow on that.

Then I was reading and was thinking possibly it could be the Electronic Pressure Solenoid (EPC). Another thing I noticed is the torque converter doesn't lock up, I was thinking it could be the TCC solenoid.

After a while the O/D light does blink, I'm gonna have it scanned tomorrow at work.

Some more reading I see both the EPC and TCC solenoid's are high wear items.

Anyone that could shed some light would be great!

-Mike

When I rebuilt mine it behaved similarly, it turned out the main harness plug wasn't fully seated. The tab was broken so I zip tied it tight and had no more issues.

So drove the truck this morning to work. I tested and have manual 1st engine braking. Actually I have manual 2nd gear braking too.

Got to work and the od light was blinking. Pulled the codes and got 2. A VSS code (forget the number) (speedo has a bit of a wobble at certain speeds, pretty sure that's the cause of that code) and a P0741. So it's throwing a TCC SOLENOID code too.

It could be the TCC solenoid, or it could be the wiring to the solenoid. The PCM can't tell the difference between a bad solenoid or a bad wire.

Well I found the pinout for the pcm and trans connector. So I'm gonna do a resistance test when I get a chance also gonna check the plug.

My main concern is the hard shifts. I don't wanna be replacing the transfer case or u joint if I can fix it.

Alrighty. So I put a new VSS in on my lunch break. Speedo is a little wobbly still but doesn't seem to be as much. The old sensor was a Ford part, so probably the original. The truck seems to be shifting better but I'll give it a few days to see. My buddy has a scanner and the computer is commanding the tcc to lock but it isn't. I'm still gonna check the ohms and go from there.

Update!
 

Well after replacing the VSS on the rear the shifting seems to be cured.. Still gonna give it a few more days to be 100% sure.

Well I tested resistance (ohms) on the TCC solenoid at the pcm connector. Well it's infinite, SO gonna order a new TCC and red EPC (since I'll be in there) and give it fresh fluid.

-Mike

Well it WAS shifting soft/normal.. then one day it was back to hard shifts. Today was soft, so not sure if it's a loose connection or what. I ordered a new EPC (red screen) and a TCC solenoid. So when I drop the pan I'll double check all the connections.