12 volt wiring 49 farmall M

Just need a few pointers. Got a project from a friend of mine that was never finished up. They put an engine out of a running and driving tractor into the one I got. He said crank no start. It has been converted to 12 volts, was wondering if anyone had an exact wiring diagram for a 1949 Farmall M for 12 volt wiring. I hooked up a battery and I have power but starter solenoid does not click and just sparks when I try to jump it. Any pointers would be appreciated.

Hello Tom welcome to YT! The number one problem is
that no M came from the factory with a solenoid. I will
link a diagram that shows a solenoid. The problem is
this one is set up so at any point the battery is
connected the starter button could be pushed and the
starter will crank. This is due to the left terminal of the
starter button being connected to the ammeter which
is always live. I would connect that wire to the terminal
on the ignition switch that power the ignition, the
resistor in this case. That way the engine will only
crank when the ignition is on, a semi-safety measure.
Looking closer I see what is probably your main
problem. By the arc spot on the small terminal on the
solenoid closest to us in the photo I trust that is where
you attempted to jump it. Sort of embarrassing but
follow the loop of that wire around and you will quickly
see what went wrong. The other terminal is the one to
jump to. That in my opinion is not the correct solenoid
for this application but it will work, providing that
powering that other terminal makes it crank.
Now secondly you did not reveal if the conversion
utilizes an alternator or generator. A photo panning out
a little and up on the distributor side of the engine
would show us what you have. If it is an alternator does
it only have one wire connecting to the large terminal
on the back or are there other wires that plug into it?
The diagram shows the wiring for the latter commonly
referred to as a three wire alternator. Just to square
everything up are you certain that the engine is free?
At the location you have it release the brakes and put it
in 5th gear, shifter to the right a down towards the
seat. Rock the rear tires back and forth with all the
force you have while watching the fan. If it moves all is
good, if not ..Houston we have a problem! I see it has a
Charlynn power steering setup, very good! My 48 has
one. You must have a unique pump mount on it it looks
like the mount sets in front of the governor and
extends down below the side channel frame to mount
the pump. FYI a make sure you take it out of gear
before you try to jump the solenoid. In 5th the starter
will not move the tractor with much force, but it will
certainly fail a test of your starer. We will see where
this gets you. Also if you send me an email I will reply
with a link for you to access some helpful
documentation to reference when repairing the factory
parts of your tractor.
Somewhat applicable wiring diagram

I did get rid of the ignition switch and wire power straight to the starter button to bypass temporarily. The big power lug was shorted to the small starter lug on the solenoid. Now I had sparks so there was power but when I held it on them there was no click or anything. I have attached pictures of what I have to work with.

I am sorry I am not understanding exactly what you are saying. Maybe I should have came right out and said it,
that wire on the small terminal of the solenoid to the outside of the tractor that loops around is attached under the solenoid mounting screw causing a dead short to ground. So shorting power to that terminal will give you a dead short. The solenoid if the type it appears to be if wired correctly needs that wire to ground that side of the solenoid electromagnet. To jump the solenoid the outer large terminal needs shorted to far small terminal. There is a possibility that the solenoid is not correct at all for this application. Those types of solenoids are available in with many different internal circuit configurations to accommodate a multitude of different needs. If by chance you are trying to operate the starter by just running power through a light duty switch intended to just energize the solenoid this will not work the contacts in one of those are far to light. Again not exactly understanding what you are explaining other than you are just possibly powering the start button from a live power source.

Edit to add: As I asked are you sure the engine is free and not locked? Those exhaust pipes that thread in the manifold do not alway seal water tight. Even if there is a can on the pipe and it sat outside water can run down the pipe and into the engine and cause rusting problems in the cylinders locking them. This is why I am asking.

This post was edited by used red MN on 10/10/2023 at 10:17 am.

Which way do I need to have it wired? Big outside lug has wire ran to ammeter which is power going in. There is a wire ran from ammeter to starter button and then wire ran from starter button to small lug on solenoid. Is it grounded wrong? I am trying to fix someone elses wiring issues on this one.

That is wired correctly if the solenoid is the type of solenoid that I think they used. If it would crank before it should be right. As you say we need to figure out what the original person who wired it did wrong or what the other problems may be. I need responses to questions I asked.
I will try this, I need yes or no to these questions.
Did you jump from the outer post to the inner small solenoid terminal?
1 Yes or No

Did that do anything?
2 Yes or No ..maybe a little short explanation would be okay on this question.

I gave you a method to check if the engine is free. Do you know if the engine is free to turn?
3 Yes or No

Do you understand clicking on the wording in my first reply ..Somewhat applicable wiring diagram.. will show you a wiring diagram?
4 Yes or No
Please open your reply with numbers 1-4 and followed by a yes or no.
Thank you!

Well you ducked out on me. Maybe you did not like my change in style, you have to understand I need certain things answered to move forward to the proper outcome. Maybe it started or you found other help. I am willing to help you over the phone if you are still having problems. I sent you an email give it a look not sure if it will go through not all your post show open email. If you have hotmail or yahoo check your spam folder for a YT Postmaster title.

All the best!
Rick