Guidance on Wire Sizes and other Rewiring Tips

Other than matching existing wires what more should be considered when rewiring an old tractor. My IH 404 needs it all. Should I worry about the connector plugs? Maybe add a bus bar instead? It does not have a resistor at the coil though one is shown in diagrams and one is on my other 404.

I have wiring diagrams (thanks) and have ordered new ignition switch, light switch, fuse holder assembly, new steering wheel and vanity cap, new starter push button assembly. The choke cable doesn't work and I need to replace it. While the dash is out is there more I should check. The tach moves a little but I don't know if that cable needs replacing. I am thinking it may be nice to add some yellow flashing lights on the fenders and maybe use the old cigarette lighter location for a new switch. Not a restoration but while I have it open just want to do maintenance and improvements.


For what it's worth my IH 404's are both wide front and though not Farmalls appear to be farm not utility tractors based on the draft controls. Thanks in advance.

I have rewired many tractors and ya i am a bit OCD to the point that when i do one it is hard to tell it is not factory . My wire color is the same as it should be and i use the correct end and plugs and even the loom is factory looking . So now your next question is where do i get all this STUFF from . all the plug in ends make and FEMAE are what is knowen as a Delco 56 series connector and the plugs or holders were used on the sixty- seventy G M cars and trucks along I H trucks some Freightliners , you can get some of them NEW when looking at USED only use the BLACK ones never the clear or white ones as the clear or white ones will turn to dust in sunlight For eyelets i only use heavyduty ones , not what you buy at the blistr pac's at the big box part stores as they are JUNK. I use delco heat shrink . A good source for top quality is Terminal Supply , now will they sell to you here i have no idea as the did only commercial accounts . and myself i usually placed orders for ends and suck in the 250 count and rolls of wire in nothing less then 200 feet Then to crimp them pesty 56 connectors ya need the special crimper to crimp them and that little sucker will make you short of breath .

If you are rewiring it as a working tractor, not a "correct" restoration I see no need for the various harness connectors, just wire straight through.

I would ASSUME the connectors are there for easy of assembly at the factory and being able to service each section of the harness separately.

As to the coil, it MAY have been changed to a "true" 12 Volt coil needing no primary resistor.

If you can ACCURATELY measure the primary resistance, a coil with a primary resistance in the 1.5 to 2 Ohms range NEEDS a primary resistor, a "true" 12 Volt coil that DOESN'T need a primary resistor will have a primary resistance in the 3 to 4 Ohms range.

The wires on my 450 were crusty and failing. I looked at a harness on here and other places... about 200 bucks was the average price.
Against the advice of some here i went to a BIG BOX store, bought 4 sizes of wire in 4 different colors. I grabbed a box of the best connectors they sell... maybe not commercial grade... but you can BUY these and not talk about getting them.

I took my time, pulled one wire at a time, used the owner's manual wiring diagram (with magnifiers) and got it wired so it cranked every time. I replaced the ignition and starter switch. The hardest part was wiring under the dash... took a while to get it right.

I spent about 4-5 hours total and about $35.00.

Will it last forever? Who knows... it's working now.

This is what I use.
eBay # 253506640828

Do a google search on "Wire AMPPACITY", chart will have several different types of wire, various
temperature ranges, whether in conduit or not, and a specified voltage. Match up your tractor's situation
and find the boxes on the Chart that show maximum amperage the wire will carry. Wire closest to what you
should use is "THHN".

I would SURE hate to trouble-shoot electrical problems on a tractor with a home-made wire harness made
from Walmart wire and connectors. I crimp AND solder connectors to the wire, and use one and sometimes 2
or 3 layers of heat shrink tubing on connections.

Marine grade wire is easier to work with and better quality than that stiff garbage from the big box store. This place ships quick and you can get lengths longer than 10':

http://www.genuinedealz.com/marine-wire/marine-primary-wire

Also a lifetime supply of connectors with heat shrink:

https://www.amazon.com/Connectors-Camtek-Waterproof-Electrical-Automotive/dp/B07H5GXR24/ref=sr_1_4?ie=UTF8&qid=1542994605&sr=8-4&keywords=600+pcs+heat+shrink+butt+connectors

A year ago when i asked about heavy duty cable ends to use on Charlene i heard nothing but crickets... so i did the best i could... didn't go to wal mart, used Lowe's and Home Depot.

I wanted to thank everyone who gave advice, I have rewired my IH 404 and only have to complete wiring to the rear light. Since those wires were protected by thick insulation they may still be useable but someone cut them off close to the fender. If I can't pull them out a little more I will run new wires.

I have a new steering wheel, new light switch, new working headlights, tellites, dash lights, key switch, push button, fuse holder and even a new cigarette lighter. ;-)

I still need to add a new tach cable, the one I ordered from YT is about five inches short and I might just add a separate water temp gauge as I could not find the original replacement part. Fluid and filter changes ahead.

But it's working now and I'll make those other changes in the fall. Got to get my other 404 running now. Again thank you to those who helped!

(quoted from post at 14:21:58 11/22/18) Other than matching existing wires what more should be considered when rewiring an old tractor. My IH 404 needs it all. Should I worry about the connector plugs? Maybe add a bus bar instead? It does not have a resistor at the coil though one is shown in diagrams and one is on my other 404.

I have wiring diagrams (thanks) and have ordered new ignition switch, light switch, fuse holder assembly, new steering wheel and vanity cap, new starter push button assembly. The choke cable doesn't work and I need to replace it. While the dash is out is there more I should check. The tach moves a little but I don't know if that cable needs replacing. I am thinking it may be nice to add some yellow flashing lights on the fenders and maybe use the old cigarette lighter location for a new switch. Not a restoration but while I have it open just want to do maintenance and improvements.


For what it's worth my IH 404's are both wide front and though not Farmalls appear to be farm not utility tractors based on the draft controls. Thanks in advance.

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