Any E4OD gurus in the group? I need some help!

Looking for electrical diagnostic tips.

1996 F250 4x4 with hydra.

I had a bad temp sensor in the solenoid pack. I was getting an error code but really wasn’t causing any issues other than a slight TC lock up issue occasionally. Replaced the pack, while doing so discovered the harness clip that holds it in place was broken off. It was like that before so I put it back together, no power to solenoid. Replaced the harness, took my time and did one wire at a time so they wouldn’t get mixed up. Heat shrink crimp connectors, with more heat shrink, wrapped with electrical tape and then wire loom. Put it back on, shifting is awful. Holds first gear, shows on my cts3 it’s in second but never shifts. I can shift into second on the manual selector though. Goes from first to third briefly, then right into fourth. Figured the remanufactured solenoid I bought was bad, so bought a brand new OEM and installed that. Same problem, now got a P1748 code.

The only thing I can think of is perhaps when I was putting new connector on, I broke a wire internally. Other possible cause is I thoroughly pressure washed under there to clean it up before I worked on it, maybe I fried a sensor but not getting any codes relevant to any sensors. Other possibility is I did not disconnect batteries when I replaced solenoid the first time (oops), maybe fried something because of that. I’ve checked all fuses.

I also have a bank transmission controller that I don’t have connected, but tried connecting it to see if it would change anything, no change.

Any tips on how to diagnose this problem?

 

is your MLPS working fine?

 

I’m not sure, do you know of a way to test it?

 

There is a wiring problem in the circuit to the EPC (Electronic Pressure Control) solenoid.

 

Do you happen to have a diagram of the harness and a testing procedure of the harness end? I did test the solenoid pack that I removed, all was well. I just can’t find any good info on how to check the harness end. I am going to pull the whole harness again and do some continuity tests, but I’d like to make sure everything is getting proper voltage from the pcm to the solenoid harness.

 

Test the wires for continuity from the PCM to the trans connector. Also check each one for short to ground and short to power.

NOTE: DO NOT put a probe into the connector where it makes the connection. This will open the pins and create a new bad connection. Probe the back side of each connector.

 

If you can, will you dumb it down for me a bit? I’m a terrible electrician. I’m learning though, trying to at least. I know the concept of testing for continuity, but I have no ideas what wires on the pcm correlate to those on the other connectors. Also unsure of how to check short to ground and short to power.

 

You need a wiring diagram. I don't have one. That will show which wire is connected to what.

To check for short to ground hold one pin of the tester to the wire you are checking. Touch the other pin of the tester to a good ground. To check short to power repeat the short to ground, except touch the second pin to a +12V source, such as the battery + terminal.

 

I think I found my problem! #2 wire on the new harness came apart, looks like I didn’t crimp well enough. That is the wire to #2 shift solenoid. I’m testing all the others for continuity before I put it back together, but it looks like I figured this out.

 

 

I'm not a fan of crimping. I think you'll have problems like this over and over until you solder these connections.

 

There’s a couple reasons I didn’t solder.

one of them was because of the banks transmission controller, there are two sets of three wires that needs to be soldered together. I couldn’t find a way to make them all join together nicely for a solder.
the wiring from the new harness is different than the older wiring. The new wiring has copper with some kind of tin core. It’s a solid piece, I can’t fray out the wiring to help join it with the old wiring. I attempted a different method to join them
together before soldering and it just wasn’t coming together nicely. Two of the wires are soldered, but after struggling to get nice clean solders I abandoned ship and used butt connectors.
I think I’ll try it again though, because you are right. They will never be reliable connections. I just need to find more videos to help me understand how I’m supposed to
join these two different kinds of wire together.

 

Crimps can hold well for years and used everywhere on these trucks
Many of us dont crimp it well enough and that can make for a fail.

I do a 10 lbs pull test after to make sure 16 ga wires dont come apart. Bigger wires need more pull to make sure it wont come apart.

Tape up the crimped areas together so the butt splices cant be stressed when bending wires or get wet

 

Hey everyone,

I’ve got a great update and closing to this problem.
I ended up soldering all of the wires. Threw the harness on yesterday, and truck is back to life shifting better than ever.

thanks for the help