Good morning Gentlemen, We have a 89' 444E JD wheel loader that has recently lost all of its drive in forward (reverse still works great) For some context and to get you up to speed on what's been done to it so far. We had a hand operating the loader pushing a small amount of snow, on his second pass after reversing he went to go into drive and nothing worked, I had him reverse it into the shop where I have been working on it since. The next day I was able to eventually get it into drive after messing around with the main harness going to the FNR solenoid/hi lo Solenoid on the Hydrostatic transmission, this lasted for about 20 minutes and then I lost all forward drive as well. The machine is now back in the shop again and I have verified good clean and correct fluid/level in the transmission, no debris in filters and even pulled disassembled, cleaned and re assembled the FNR solenoid as well as verified voltage to it in reverse and drive which all checked out. I had found a few small breaks in the harness going from the other Daikin solenoid valve that is in the engine compartment near rear "firewall" and those have been fixed but no change strong reverse and no forward gears doesn't even attempt to move forward. I feel like this is a simple electrical problem that I am overlooking? any help or ideas are greatly appreciated!
Welcome to HEF PINEDALELUMBER . I posted a screenshot from the Hitachi equivalent LX70/80 manual. It may help or not. The Deere 444E operation and test manual is TM1421 . .
Switch the park lockout relays and see if your issue changes direction. Also, check that the FNR is sending the voltage in forward.
Check your ignition switch. On my Volvo L90C I lost forward and reverse yesterday. We had cleaned up some corrosion on the contacts a few weeks ago and it was working fine until yesterday. I was wiggling it with machine running and it would engage and disengage. Looks like I need to get back into it again. I think I'll end up replacing it. Let us know what you find. It's often the simple things.
A few updates, haven't had a lot of time to work on it. First thank you all for the great suggestions! I checked all the wiring and the relays like suggested and found no issues, as well as I checked my ignition switch and all checked out there. I ended up pulling both of the Daikin solenoid valves for the FNR and found the rear one to have major rust internally. I bought a used set of 24V solenoids (mine is a 12 V system) off of ebay and was able to rebuild both of my solenoids with some better condition internals from the ebay solenoids. Now I have working forward and reverse again! But... the machine is now getting stuck on the hi side and throwing hi/lo control light on the dash (it has done this a few times over the years but usually went away right away) the machine is still quite unusable with only high side. If you gentlemen have any suggestions on ideas of getting it back to Lo side or where to even start with this issue any help is still appreciated. Thank you!