Farmall M wiring harness

appraiser

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I think I need to get a new complete wiring harness for my M. I keep having trouble getting it started. I clean the points and plugs, charge the battery, etc. and it will start. Next time it will not start. It has 12 volt battery, voltage rectifier, and alternator. Think I need to put in a new harness. What are thoughts, suggestions or recommendations?
 
Brillman Co. makes harnesses. from reports,they are top notch.Check out these guys(YT),they may have harnesses.However,It might be just as easy to make your own if you don't care if it's 'original',or not.
 
How long does is set between starts? If it sets for extended period of time points are known to develop an invisible film that will prevent them from contacting.

Cleaning points, plugs, and charging the battery should not affect the wiring harness. Next time try cleaning just the points.

However, if it is an original or cobbled up harness, replacing it will likely prevent future problems. Mr. Murphy's law clearly states that if it does give a problem it will be at a place or location farthest from home and farthest from the tool box. The harness is not that complicated and would not be difficult to make from some wire and connectors. #10 wire from generator / alternator output to ammeter and ammeter to battery connection at starter switch. #14 for the rest of the wiring.
 
The wiring on a tractor is so simple I make my own. But you need to fill in a few blanks for us to be able to help you help your self.
#1 what alternator do you have?? 1 wire or 3 wire or something other then a Delco 10si
#2 voltage rectifier?? Do you mean a diode or a ballast resister???
#3 as for not starting as in battery dead or is there a problem in the distributor like say burned points??
 
(quoted from post at 14:48:09 12/02/18) I think I need to get a new complete wiring harness for my M. I keep having trouble getting it started. I clean the points and plugs, charge the battery, etc. and it will start. Next time it will not start. It has 12 volt battery, voltage rectifier, and alternator. Think I need to put in a new harness. What are thoughts, suggestions or recommendations?

Im no expert, but nothing you mention doing to get it running would be effected by the harness, unless the battery isn't getting charged. What does the harness look like? Are the wires hard and brittle, does the insulation break off when you bend it? Are the wires loose in the connectors? If so, then you MAY need a new harness.

My 450 wouldn't start, AND the wires were as described above, i mean they were BAD. I bought heavy gauge wires in 2 sizes and 4 colors, the best connectors i could find and pulled 1 wire at a time. I broke out the manual, got magnifiers and wired under the dash (the hardest part). Parts cost about 40 bucks.

BUT IT STILL WOULDN'T START!!! The battery was 2 years old...I took it in, it had a dead cell..... so now i have new wiring, new battery, and Charlene cranks every time... sooooo far.

Bottom line... find out what's making her not start... go from there... throwing parts at the problem won't fix it.
 
You mention charging the battery. Is it not holding a charge. Its possible its taking all its power to crank the tractor and doesn't fire the points. Nothing you say you do to start the tractor indicates a wiring problem unless there is a problem that's causing the battery not to charge.
 
It probably sets for 2-4 months between starts! The wiring harness appears to be original with some splices. There is no wiring for lights. If I hold the starter lever engaged a little long you can see smoke coming out of the start button area.
 
Why not make your own harness?
Search the web for www.charliesrepair.com
He is member on here, great guy!
Really nice simple laid out wiring diagrams to wire up old IH tractors like yours. Unless your going for the restored look.
 
(quoted from post at 21:50:11 12/03/18) Why not make your own harness?
Search the web for www.charliesrepair.com
He is member on here, great guy!
Really nice simple laid out wiring diagrams to wire up old IH tractors like yours. Unless your going for the restored look.

I made my own, didn't know about the YouTube video, but mine cost about $40 and it took me about 4 hours total, over a couple days. Wasn't going for restored look, used zip ties to bundle wires.

But..... your M if properly tuned should turn over a few times and start.. my 450 does, now.
 
If you have smoke coming from the starter switch you likely have a bad connection that is heating up due to high resistance and will fail eventually. I'd consider switching over to a starter solenoid and push button. Also, I would not jump to the conclusion that the wiring is bad, if you are getting it to start after cleaning the points or charging the battery - sounds like the points or battery/charging are more likely culprits.

Do you know the battery is charging? Read the voltage at the battery while it's running and see if it is 13.5 to 14 V.
 

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