2000 2X4 3.0 4R44E No Reverse after rebuild but has engine braking

[ReddyK]

I have a 2000 Ranger 4X2 3.0 with a 4R44E that wouldn't move in any gear except L1. So I took it out and rebuilt it. The only bad parts were forward clutch and the coast clutch frictions and one thrust bearing was toast. The rest of the transmission looked good except the servos were full of sludge. I disassembled and cleaned everything including the valve body and all the spool valves moved freely. Checked the resistance of all the solenoids and applied 12V to each and made sure they all clicked. 100% of the seals were replaced and a reman converter. I reused the pump and bands since they looked perfect. There are no DTCs and the OD light is off.
The truck has all the forward gears but no reverse. It clunks when putting it in reverse like it is going to work but it does not. I checked the line pressure as listed below.

Park Idle 135 psi WOT 160psi
Reverse Idle 180psi WOT 260PSI
Neutral Idle 135psi WOT 300psi
Drive Idle 135psi WOT 160psi

I have rechecked the reverse band and servo but I am at a loss as to what is wrong. Any suggestions would be very appreciated. I forgot to mention that it does have L1 engine braking, indicating that the low/reverse band is working. I happen to have a spare Digital Transmission Range Sensor and it made no difference. The brake lights work with both. I unplugged the transmission wiring harness and the REVERSE WORKS but not with the computer plugged in.

Here are the EPC pressures that i measured. The WOT pressures seem a little low in all the gears according to the chart below but, I am not sure if these pressures tell us anything that is a possibility to not having reverse.

Park Idle 55psi WOT 60psi
Reverse Idle 45psi WOT 80psi
Neutral Idle 60psi WOT 80psi
Drive Idle 50psi WOT 70psi

I have read nearly every thread that sounds like a similar problem but, I can't find any that are my exact problem. Any help would be appreciated.
Thank you,
Steve

 

[JK080]

If you still have no reverse or forward but it does move in manual low the input sprag has failed.

Check out this thread.

If all forwards work like they should but no reverse you could have a problem with the 2-3 shift valve end plug not correctly installed.

Check this thread out for the end plug issue.

Or the reverse modulator valve sticking or a problem with the reverse servo itself.

 

[ReddyK]

@JK080 Thank you for your reply.
It finally quit raining and I pulled the valve body again. The 2-3 end plug and retainer are in the correct positions. The Reverse Modulation Valve is free and smooth. The Boost Valve is also free and smooth. I have an extra transmission and will swap the EPC, SSA and CCS solenoids before I put it back together unless, someone has another idea?
I just don't understand why the reverse works when the harness is unplugged but, not with it plugged in. I feel like a solenoid is mechanically stuck or something as everything check good electrically.

 

[ReddyK]

After replacing the EPC, SSA and CCS solenoids there was still no reverse. Fed up, I went to the junk yard and bought a replacement valve body. Swapped it this afternoon and the transmission works as it is supposed to. So, there was something wrong in the valve body that I could not find.
Thank you for all your help.
Steve