D17 Wiring and Series of tractor Ques.

I just bought an Allis D17. I know it runs well, because I drove it around 45 miles to get it home. It was a pleasant drive, but the last half hour was a little tough since the lights dont work, and I ran out of daylight. Anyhow, I got it home and put it right in the garage to fix the lights. Someone cut all the wires near where the headlights are mounted, near the radiator and the real light as well. I was able to run my jumper cables to one light and to the battery and it lights up.

One of the first things I found, is that the fuse holder on the dash was broke. Jumping across that fuse holder made the little light on the dash light up. But no voltage to the headlight wiring, with the light switch pulled to ON.
I'm not 100% sure if the headlight switch is fed off that fuse, but I would suspect so.

So, it appears that the light switch is bad, because the wires near the headlights have no voltage, even with that switch turned ON, and the fuse holder temporarily bypassed.

I'll replace that fuse holder, and the switch if needed. But I have no idea what size fuse is supposed to be used. Can anyone help with that???? (My guess would be a 15A or 20A).

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Ok, enough on the lights, that's a relatively easy fix, once I can trace the wires. I also know the starter solenoid is weak, and dont turn the starter on the first try, so I'll just replace that too.

But another question. While looking for a wiring digram online, I noticed that many times the SERIES of the tractor is mentioned. It appears there is the regular D17, and series 2, 3 and 4. How do I determine what series I have? I assume it involves the serial number tag. WHERE IS THE SERIAL NUMBER TAG located?

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Lastly, about the Positive ground

I've never owned anything that had a POS ground before now. I know enough about electricity to know that the circuits are wired the same, just the polarity is reversed, and that lights and motors run fine with either polarity. (But NOT electronics, such as car radios or electronic ignition). But the D17 dont have electronics, so the only thing involved is the generator which must be correctly polarized.

However, someone told me that you can NOT tow or pull with a NEG ground vehicle, if using a metal tow strap or a chain. In other words, the tractor has a POS ground, and my truck has a NEG ground. So if I use one of them to pull the other and use a metal chain, something will be damaged in the electrical system on either the truck or the tractor (or both). This has me puzzled. In some ways it makes sense, but in other ways, I never heard of such a thing. How true is this?

Thanks

About the towing opposite polarity with a chain- towing won't make any difference.
HOWEVER, if attempting to jump start one or the other, the chain will create a dead short.
HTH
Willie

Serial # is on the bell housing next to the engine on left side of tractor while sitting in the seat. The serial # will determine the year and series of D17 you have. If headlights are on radiator you more than likely have a series 1 or 2. I am not quite sure if the 3 had them on the radiator but I know
the 4 had lights on fenders.

All D17's should be 12v neg ground. Lights on the radiator make it a series 1 or 2.
AaronSEIA

Both of my d17s, series I & IV, are positive ground.

If it has a generator it probably is positive ground. if it was changed to an
alternator it would be neg ground.
You starting problem could be the ignition switch. I have an early D14 with a
pushbutton start switch and some times it acts up. I bought a new switch for it
and since then it has worked fine even though I have'nt install the new switch.
You light wiring problem can easly be diagnosed with a couple of jumper wires and
a voltage meter. Just trace the current until you lose it, then jump it. Power to
the fuse? power to the switch? power through the switch? power from switch to
lights?
Love my D series tractors. LOL Bob

Willie, tell me how will the steel chain create a dead short when using jumper cables to start the engine on one of them??

Chain towing thing is nuts!

Series I first style...1957-59 Serial number 1001-23363
Second style....1959-1960 24001-31625
Series II 1960-1962 32001-41540
Series III 1962-1964 42001-72768
Series IV 1964-1967 75001-89213

Series I, II, III had live pto and hydraulics, with Power Director (hand clutch). Series IV had independent hydraulics with side-mounted constant-running pump.

Tried to draw it out on here, but didn't work.
Original post says tractor is pos gnd, truck is neg gnd. If trying to jump one from the other & connected with a chain, current path will be truck pos thru jumper to tractor pos,(gnd) then thru chain to truck neg,(gnd) ZAP!
Also truck neg(gnd) thru cable to tractor neg, then thru chain to tractor pos(gnd) ZAP number 2.
Willie

If you are gonna jump it and pull start it, then jump it first for a while. Unhook the cables, then tow it. But reading your post, all you are concerned with is pull starting. That doesn't matter. If you are worried, go buy a short nylon tow strap. Or just buy the $10 solenoid you need to replace the one you think is bad. If it turns over slowly, I'd be more inclined to think it's a bad ground or battery rather than a bad solenoid. Those are nothing more than an on/off switch.
AaronSEIA

willie, that will only happen if you are using the chain as connection for a ground and only using one battery cable to the hot posts on each battery.
hook battery cables + to + -to - no harm to either battery. if both are the same voltage.

What are you smoking or drinking??

Willie is 100% correct. Remember the tractor is positive ground, the truck is negative ground. With jumper cables connected positive to positive and negative to negative on each battery, pulling the chain tight makes a dead short through the jumper cables. Positive on the truck connected to the frame of the tractor. Chain from tractor to truck shorts the trucks positive to it's negative.

With jumper cables hooked up ANY metal touching both tractors becomes a conductor. Rule #1 of jumping is the vehicles DO NOT TOUCH. But I'm not sure the OP is wanting to jump and pull at the same time. Not sure how we got to the conclusion.
AaronSEIA