wiring kit

I bought a new wiring harness for my 1951 Farmhall Cub. Problem is - it does not come with instructions.
It should be obvious - take the old one off and just add the new. But this old machine has been cobbled together electrically, and most of the original wirng has been replaced with goodness knows what.

So I need some help making sure I connect the right wire to the right place.

There is a thick black wire, that is spliced into two, so I assume it is the headlights. Right?

Where do these fit?

A thinner black one.
A black with white check marks.
A yellow with blue and red check marks
Yellow with blue check marks.

John,

There's no way to know which wire is which by color and a vague description. The wiring harness manufacturer could have used any color wire for any function.

In fact, on a tractor from that era, all the wires are supposed to be the SAME COLOR!!! Original wires were insulated with woven cloth, not plastic.

You're going to have to get out the owner's manual with the wiring diagram and start working through it. If the wire has the right connector and is long enough, it's probably the right one.

I don't have one specific to a Cub or I'd share it, but you need to get a wiring diagram. Most of your wire will be black, but IH used different colors for the wires in the long harness that runs from the regulator back to your ammeter and switches. (The IH diagram for my SuperC lists a natural color with green tracers, for example, and another one natural with red and black tracers, so you can keep track of which is which at the different ends), but you'll need a diagram to tell you where the ends hook up.

From your description it's a safe bet that the split black wire is for yout head lights. In all likelihood, the thinner black wire, if there's any length to it, carries the current to your coil or, in the case of a magneto, runs back tothe switch to ground it out. If it's a short wire, it's more likely a jumper from the generator to the regulator.

Are the three colored wires all in one harness? IF so, this would be the hookup from the regulator to the ammeter and switches. Since these probably aren't the original colors you you'll have to do like mkirsch suggested, which is hook them up on the regulator end in the way that fits best and then, using a diagram and following your colors, hook them up at the back end to where they belong.

I'll look around and see if I can find a link to one of the Cub sites and post you a link to a diaagram if I can find one.

HTH

don't know were ya got your wiring harness at but the factory colors are this , LIGHT BLUE WIRE IN 12 GA. IS FROM ARMATURE TO REG. GAUGE .YELLOW IN 14. GA. IS FROM GEN. TO FIELD ON REG. GRAY QWIRE IN 12 GA. IS FROM REG TO - SIDE OF AMP. GA. RED WIRE FROM + SIDE OF AMP. GA. IS TO THE BATTERY SIDE OF THE STARTER SWITCH.LIGHT GRE3EN WIRE IS FROM THE L TERMINAL OF THE REG. TO THE ING. SWITCH IN 14GA. BLACK IN 14 GA. IS FROM ING . SWITCH TO THE COIL ON THE PLUS SIDE IF IT IS STILL 6 VOLT AND IF CHANGED TO 12 NEG. GROUND THEN TO THE - SIDE . NOW FOR CORRECT LIGHT WIRING TO THE LIGHTS THE EXTRA LIGHT GREEN FROM ING. TO FUSE AND LIGHT GREEN TO THE SWITCH TO BATTERY SIDE OF LIGHT SWITCH BLACK IN 14GA. FROM THE TL. POST TO TAIL LIGHT THE VILOET IN 14 GA. TO HEAD LIGHTS FROM THE HL POST. Then ya make up a white wire in 14 ga. for head light ground . These colors and sizes came from the I H shop manual GSS 1308 . I gave up tryen to buy wiring harness after the second one that was not correct and had to add butcher to make it work . Making up one for a Cubby is not hard to do and if ya hunt around and find the heavy duty terminals they are better then most . You can even find good wirein the correct colors but not from places like auto zone or any of the big box stores.

Here's a link to a couple of diagrams I was able to find. They'll be down the page a little ways. One seems to be for a magneto, the other for a coil/distributor ignition.
Diagrams

to the thread headed "Bob's wiring diagrams" and go down until you get to his link, then punch up what he's got there for As and Bs. Got an idea they might be helpful. He's moved them recently and I wasn't able to find them earlier, so strike while the gods are smiling.

Good luck! And let us know how you're makin' out.