Rewiring from selector switches to solinoids, fixed it. Both reverse and forward have been working well for a couple months. Must be a problem with OEM wiring harness. You must completely cut both ends of OEM hot and replace with wire. Leaving old wire hooked up caused it to lock into gear among other things.. Gotta be a short or something. Hope this helps someone else.

Thank you.
K005d05653y
H80XM

ok one thing we didn't do is determine what transmission is in this unit, it's either a 2 speed power shift or just a normal powershift.
If there is a switch on the dash with transmission symbols or other symbols indicating hi or low or 1st or 2nd speeds this would be a 2 speed control switch.
in either case it probably has a transmission control module in the dash area located on the right hand side probably mounted underneath the firewall kick panel area.
There is also a mention in a schematic showing a 10 way dual micro relay base supporting forward and reverse relays.
(this is probably later serial numbers.

After i found a parts breakdown diagram it does show this small module mounted underneath the dash on the right hand side. There is a high possibility your loss of or weak signal may be due to that being either bad or the connector is corroded. The connector on it will be a rectangle shaped 12 wire conductor molex type plug, it will more than likely have only 10 wires hooked to it, the diagram shows it has 2 open conductor slots not being used.
terminals 1, 2, 3, 4, 5, 7, 8, 11, and 12 are being used, terminals

Now it could have a different shaped deutz type plug that is more rounded utilizing all 12 wires

So can you give me a serial number off the truck?
This would be very helpful in determining what might actually be on this truck.

Well, I got one solid day of working great.Moved 20 trailers without flaw. Now it is acting up again.

All works good until coming out of forward then neutral is still forward and reverse is neutral. If i shut off and restart neutral works again as does reverse. So I have to shut off every time I want to put it in reverse.....
Any ideas?

good deal
yeah sometimes cutting open a harness to trace down a bad spot in wiring isn't the most cost effective and quickest way to fix one but i think you did the next best thing. Isolating the circuit enough to know which wire was bad and just running a new one is sometimes the quickest and best course of action to get it back going faster.

and yes the directional switch has always been a weak point in these trucks, since it gets used more and takes most of the punishment during use i'm suprised they last as long as they do sometimes :o)

Fixed.
Did two things
1. The forward position on column selector was not engaging far enough after I removed,tested and reinstalled. so a little adjustment go it working again. I think this is a problem I created in tracing down the real culprit.
2. Added a wire from forward switch (blue) directly to hot side of of forward valve connector(green). There must be a week connection between them.
The thing that really stumped me was having power to both connectors on valve body. Shouldn't have assumed they are getting the power they needed. Switching connectors and reversing the problem started reveal the area to focus on.

Working great now.

Swapped the forward /reverse switch and no change.
Are there gain setting for forward and reverse. Maybe gain is set higher for reverse?

I just jumped the ground side of the connector(green/forward valve) and no change. I then jumped the positive side and bingo it works. So I'm thinking that just because I have switched voltage going to forward valve it must not be enough. Maybe a loose connection or the forward/neutral/reverse switch is failing in forward but not reverse. getting closer.

The 12v does switch on and off with selector. I haven't found out where the ground goes to yet. I want to clean it or maybe just add a new ground. Don't want to fry anything just yet....At this point at least I can use machine by switching connectors on valve body. Any advice on finding ground point for wiring harness? Does it go back to brain box in engine bay maybe?

if you're getting 12v at the connector full time then check the ground side with the directional switch engaged.
Some machines used ground switching instead of power side switching so make sure you have ground when direction is selected and also the 12v signal on the other side of circuit.
Might want to run a resistance check on the circuit, it may read 12v but not be able to carry the load to pull the solenoid in.
Faulty connection or bad wire or switch.
Since the problem moved to the opposing solenoid that rules out any issue with the solenoid valve or control valve spool issues.

Update. I reversed the green and brown connector on valve body and it reversed the problem. Now forward works all the time and reverse is delayed. The control is also backwards.

This leads me to believe something is wrong with the green connector even though it has 12 volts.....maybe a bad ground or some other switch?