no junction box?

I am converting the Farmall M to 12V, and having a trouble wiring. I think there is not a junction box anywhere near the ammeter/lightswitch box. If I don't wire any lights right now, can I just not use a junction box? Anyone have a photo of their junction box? I just want to start the tractor and use it ASAP, so if I could use it without the junction box and lights, that's be good enough for right now. Or maybe that will hurt something or maybe that won't work?

I don't use a junction box all I do is wire it so the amp gauge has the load going to the ignition switch and from the ignition switch to the coil if a 12 volt coil if 6 volt you ad a ballast resister

This is how it's wired now.

There's no fuse in there right now. For the lights, this round black knob one can replace the original clear glass cylinder one, right?

You may have a bad new gauge then

This is what you need Choose the alternator version. No junction boxes were used, but sure can be if you want. Waterproof is best. Jim
bob M diagrams

There are a couple problems with the diagram:

On the left, the starter switch, the battery cable and the feed to the ampmeter go on one stud.

Only the starter cable goes on the other stud.

On the right, the ignition switch and alternator connect to the other side of the ampmeter.

From the ignition switch, connect to the ballast resistor.

From the ballast resistor go to the + terminal of the coil.

From the - coil terminal, connect to the distributor lead.

This is assuming you are using a "one wire" alternator.

The wire from the starter switch to the ampmeter, and from the ampmeter to the alternator need to be #10. The rest can be #16.

If you want to use a fuse, put it between the ampmeter and the ignition switch, a 15 amp will be sufficient.

I wonder if I can do this for a junction: Use the resistor that is not being used now (right next to the light switch screw) that used to be used for the cut out or whatever. Could I use one screw end of that resistor as a junction spot? If I can do that, then I can go ahead and put the lights on right away and complete all the wiring now. I bought a harness kit and it is all set up to use a junction screw between fuse and ammeter, so I'd rather do that than not. What's my other option, to cut the round metal ends off and splice bare wires together and tape it?

Yes, you can use the resistor screw as a junction.

As long as it is solid, not going to fall apart or touch anything metal, it will work.

You can also get a small screw and put through two or more round terminals then tape it up good.

Using an unused stud also works. Just be sure it's not connected any way.

From the factory a Farmall "M" has no junction box. The wires are connected to items inside the ammeter box. Use insulated terminals to connect bare wire ends if needed, don't twist them together and cover with tape. As Steve mentioned your diagram needs lots of corrections. Use Jim's suggestion to follow Bob M's diagrams.

Wiring a Farmall "M" is pretty easy.

ok, thanks guys, I think I'll try connecting and taping them. I guess I don't understand why it's not one piece instead of junction block ends. Instructions are for ignition switch to light switch. Light switch to fuse. Fuse to junction block. Junction block to ammeter. I hope I'm right im assuming those two ends in the juntion box are supposed to be connected to each other?
Steve, I'll also change the starter wire to be by itself and wire to ammeter to other side. Thanks.

I'm still alive. :shock: I sat in the tractor seat for a long time getting up the courage to press the start button. Thought the whole thing might blow up. No. Started right up, very easy and fast start. Running really nice just sitting there in neutral. Ammeter shows absolutely nothing the whole time. Hard to tell because it's daytime, but I think lights are also not working. I still have the hood off, and noticed after it was shut off, there was constant smoke coming from base of muffler maybe about 6' above exhaust manifold. Why would it be smoking from there so much and keep smoking long after tractor was shut off? Coming out the seam where the muffler is attached. What a HUGE difference in starting though! WOW! I did an electronic ignition, too.

Went and started it again. Now that I think it won't blow up, I was able to pay attention the whole time to the Ammeter. It does move a tiny bit when ignition switch is pulled on and then goes a little bit negative when light switch is on, and then when starter switch is pushed, it jumps up fast to where it should be and holds for a little bit, and then fades to zero and stays at zero.

(quoted from post at 11:56:37 08/25/19) Went and started it again. Now that I think it won't blow up, I was able to pay attention the whole time to the Ammeter. It does move a tiny bit when ignition switch is pulled on and then goes a little bit negative when light switch is on, and then when starter switch is pushed, it jumps up fast to where it should be and holds for a little bit, and then fades to zero and stays at zero.

Click to expand...

That's great, I'm always so happy when things don't blow up! Sounds like you did a good job on the electrics and now have a dependable M. Taken it out to try the sickle bar?

[quote="RedMF40"
Didn't take out the sickle yet because it's supposed to rain a lot tomorrow. Will be trying it all out on Tuesday unless forecast changes. I was exhausted after the M was all done today and took a one minute nap on the couch. I was dreaming I was looking in a drawer for the carrot grater but I kept asking, "where's the alternator? Where's the alternator?" !!! Calling the grater an alternator. I got a little too much tractor on my mind. Looking forward to a break from tractors on the brain tomorrow. The alternator was a tough one to get installed because I had to get a smaller 1/2" wide instead of the 5/8" that came on it, and the 1/2" one was bigger circumference so the belt was TIGHT and made for a hard time. Did the alternator, both belts, electronic ignition, new coil and resistor, spark plug wires and plugs, 12V battery, all wires, ammeter, and new lights. I think I would like a new light switch maybe. Changed all fluids except antifreeze. The oils were thick and chunky and the color of milk chocolate! Never saw anything like that! Repaired a piece off of air cleaner. I'll tell you what though, I just can't get over how nice and easy and fast it starts now. Seems to run better, too.
I saw a 10-20 for sale in WI but it's $1,200 and it has ugly rubber tires. Are you getting your engines on the two vehicles swapped out now on your big hoist?