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Ford 4400 1967 Diesel wiring issues

629 Views 6 Replies 2 Participants Last post by  pacwolf
I have a Diesel Ford 4400 1967 model tractor.

My instrument panel wasn't working when I bought this 4400. I have found a number of issues with wiring being connected to wrong things. I fixed the oil light tot he instrument panel and traced several other wires to find some issues i have question on.
The wire from the Generator/Regulator to the generator warning light to the instrument panel not working. Can I replace this wire and if so what gauge wire would I use as I think this wire is broken somewhere inside the harness.

The wire from the Regulator to instrument panel ground can this also be replaced and what gauge wire since I think this is also broken inside the wire harness somewhere. When I test with a wire toner it seems to stop around where the harness connector is.

I have attached a photo of 2 wire coming from the top of the transmission housing. Anyone know what this is and how it is supposed to be connected? I may be wrong but this it is something to do with the key starter safety switch.

Thanks you
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I would test it with an ohmmeter first, but yes, if the wire is bad you can replace it. It doesn't draw much, maybe 35 watts tops, which is only about 3 amps, so you should be able to use 18 gauge or heavier wire without a worry. If you want to be extra safe go with 16 gauge.

Yes, that can be replaced as well. I would go with a16 gauge wire there, as it is actually only the ground for the two instrument panel illumination bulbs and for the voltage stabilizer, and those cannot draw more than 5 amps either because the main power wire from the key switch to the instrument cluster has a 5 amp in-line fuse in it.

Your picture didn't come through, but you are correct that the two wires coming out of the top of the transmission are for the starter safety switch. There should be two wires coming down from the bottom of the dash in that direction and it if starts without them being connected to the safety switch wires then they are most likely just connected to each other to bypass it. If it has a Select-O-Speed transmission the starter safety switch only allows the starter to turn when the gear selector is in the Park position. If t has a manual transmission (6 speed, 8 speed or 4x4 manual reversing trans), it only allows it to start when the hi/low shifter is in the neutral position, and if it has the 4x4 torque converter auto reversing transmission it only allows the starter to turn when the main shifter is in neutral.

thank you for the info on the gauged wire. I will get 16 gauge to be save. By the way I forgot to add the photo so here it is. I will have to trace the wires as I have found some in the wrong place. where does the wires go from the trnsmission housing as there are two. see photo.
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I will look around under the hood to find any loose wire from the switch and starter solenoid. Thanks for this information as I couldnt find anything in the books. That will be my task for next week.

I found a full wiring harness under $100 and thought maybe I should just replace them all since they look like all original and the plastic coating is getting brittle . I have posted the link here. Not sure if this would work but seems to be pretty complete. Wiring Harness for Ford '65-74 Diesel Tractor 2000 3000 4000 3400 3500 3550 4400 4500...
I didn't think about the key switch. I will trace the wires and mark before I pull it just in case. I don't know if its original or not. I have provided a photo I took. I thought it was original but not sure how to tell.
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