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 banks transmission controller that I don’t have connected, but tried connecting it to see if it would change anything, no change. No change/very little change when I switch tunes on the hydra.

Any tips on how to diagnose this problem?

 

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