555 D ford backdoe shifting problem

TractorTech · Dec 9, 2023

eKretz said:
Yeah, I figured likeliest culprit is coil too. I'm surprised the resistance would change when it gets warm is my only qualm. I figured it would overload immediately if there was an issue there. And yes, looks like the fuel tank needs to come out to get to those solenoids. I was hoping it might be more like an hour or two job, but it just got longer... Typical.

Draining the tank, if full, and removing the hood are the hardest. Oh, and removing the three tank bolts underneath.

Test the controller first, may find out something is getting hot and failing there.

eKretz · Dec 9, 2023

Definitely. I've determined all the wires I need to check so that I can do most of the troubleshooting before needing to pull everything apart. I've got the sheets from the service manual printed for checking out the controller as much as I'm able to as well. Might be able to get to it this week, I hope. Fingers crossed!

eKretz · Dec 10, 2023

Well, cold resistance across the coil is 9.4 ohms. No problem there. Both sides are 25 Mohms to ground too. I'm gonna fire it up and drive it around a bit and see if that changes.

eKretz · Dec 10, 2023

After about 20 minutes, forward went out, as usual. Checked resistance at the forward solenoid coil just after and it's sitting at 10.1 ohms. Both sides of the coil to ground are high Mohms still. I have a good input signal to the control module at battery voltage from the shuttle switch when the switch is placed in forward. No output signal from the module output side. If I do the reset, then I get a split second of output, then it shuts off. I also monitored the current on the forward solenoid coil while driving around. It stayed right around 1.4 amps the whole time until it quit working. This leads me to believe that the control module is the problem. Wish they had not potted the bastard.

Edit: I may try de-potting it and attempting a repair. The compound doesn't seem that hard now that I'm inside where it's not 30°.

TractorTech · Dec 10, 2023

A little heat will help as you have found. Not much to the controller. You will probably be able repair.

eKretz · Dec 10, 2023

Yeah, I figure if I can't de-pot and fix it, I'll just make my own. Basically just a delayed activation switch as near as I can figure. In a pinch I could probably just send 12 volts to the solenoid and be fine.

TractorTech · Dec 10, 2023

The delay essentially modulated the shifting in 3 stages, so yeah you could bypass.

eKretz · Dec 10, 2023

I'll be GD'ed. Didn't see that one coming. Doesn't help much though. Doesn't seem to be any availability on that part number either.

TractorTech · Dec 10, 2023

eKretz said:
I'll be GD'ed. Didn't see that one coming. Doesn't help much though. Doesn't seem to be any availability on that part number either.

View attachment 837481

What? That it was made by Kubota??? The transmission on C and D series TLBs, TLs and Industrial Tractors between 1989 and 2000 were built by Kubota, and yes, the parts in that transmission are not used in any Kubota tractors.

Note, that the transmission part numbers start with "K" for Kubota.

eKretz · Dec 10, 2023

TractorTech said:
What? That it was made by Kubota??? The transmission on C and D series TLBs, TLs and Industrial Tractors between 1989 and 2000 were built by Kubota, and yes, the parts in that transmission are not used in any Kubota tractors.

Note, that the transmission part numbers start with "K" for Kubota.

Did not know that, thanks for the info. I did notice what looked like a Japanese inspection mark on the opposite side of the metal case. I am pretty impressed with the quality of the circuit board. Very nicely made, and every component and its value where applicable are screen printed. Not like the ***** from China that I see mostly these days.