M38A1 Wiring

[Don X]

I need to rewire my M38A1. It still has a 24 volt system but it's not a restoration quality Jeep. I've been looking at wiring harnesses but everything that Walcks, Kaiser Willys, etc. carries is way overkill way expensive for what I'm doing. EZ Wiring has some reasonable kits but I can't tell if they'll work with the 24 volt systems. Can anyone recommend a generic wiring harness that works with 24 volt? Not concerned about water proof qualities. Only that it will work with24 volts.

[mdainsd]

Unfortunately, all the end use items, like lights, sensors, switches, generator, regulator and gauges have unique Military style connectors. The non military after market harnesses, do not.

There really is no middle road.

[spillmk1]

The 24v really doesn't have much to do with it. A harness could be built using standard 14, 12, 10, 8 gauge wiring as needed. But like stated above, all the pigtails/connectors on your "stock" items like lights and gauges would have to be clipped and another means of connection found.....plug, soldering, splice, etc...

[dpcd67]

Here is what you should do; pay $850 for a new harness.
OR, buy a new M35 truck harness for $60 and make that work. Remember that all military harness wires are numbered the same.
I am doing that for my M38 now. Not as hard as you might think; take it one wire at a time.

[Don X]

Here is what you should do; pay $850 for a new harness.
OR, buy a new M35 truck harness for $60 and make that work. Remember that all military harness wires are numbered the same.
I am doing that for my M38 now. Not as hard as you might think; take it one wire at a time.

I'm not familiar with harnesses. What do you mean they are numbered the same? Also, an M35 is a much larger vehicle. Won't the harness be too long for an A1?

[skyjeep50]

One of the features of the M Series military vehicles is commonality of parts including wiring circuits and electrical components. The wiring circuits are identified by small aluminum tags embossed with the circuit number. I you don't have the manuals for your M38A1 you can go over to Willys M Jeeps site www.willysmjeeps.com and sign in - in the "Downloads" section there are most of the manuals you need plus extensive technical photos and other info to help you. Included are wiring diagrams. The M35 truck has pretty much the same wiring system as the M38A1 jeep - wires are longer of course - but the circuits #'s will be the same. I rewired my M38 using a custom new military harness and it was pretty easy job. Plug and play. With a M35 harness you'll probably want to identify and keep the ends of the harness intact for easy connection to lights, etc., and just shorten the middle of the circuits. I also have a M38A1 and on occasion have switched electrical items from one vehicle to the other. Makes maintenance and quick repairs easy.

[dpcd67]

Yes, what he said; a #17 wire from a tank, truck, or jeep, goes to the head light on all of them.
Of course the truck wires are longer; look at my comment "make it work". You want to save money don't you? That means you have to get involved in the process.

[PrairieWheeler]

I know the thread is old, but where are people finding M35 wiring harness with Douglas connectors for ~$60 to modify for M38/M38A1?
I have a M38-CDN and it needs the wiring redone and ~$800 USD does not sound good to me.

thanks,

[AFM38A1]

The 1955 M38A1 I just bought was in very good shaoe. Good body, no rust, a very solid truck. At a very good price...at least compared to the ads I see online at various sites.
The seller had some items sorted at his expense since he wasn't a mechanic, ...basically a tune up and new sending unit.
Anyway, the main issue the shop found was bad, ancient wiring. He recommended a new harness.
So I said "Do it".
It's being custom made out of the correct wire with all the connectors.
$800 seemed a fair price. Installation is another couple hundred.
Some of my other old cars are older Mercedes, so I thought it wasn't a bad price!
A couple of years of Mercedes in the 90s had bad harnesses (imagine all the connectors on a luxury car) and the harness itself is something like $3500-4000...plus installation.
So, keep costs in perspective.

[dpcd67]

Personally I can't afford the high shop rates for jeep maintenance, so I learned to do it myself, including making wiring harnesses from M35 ones (they are cheap), and doing the installation. It is actually easy; you just need a 4 stab crimper and some terminals; readily available.
But you can buy the wiring harnesses already made.
True, costs are all relative.

[Ken Perkins]

don't throw the old harness away...the Douglas shells and grommets have value...

[jnissen]

Or if adventurous and didn’t know any better you can custom wire a harness. Not difficult but does help to create a full schematic ahead of time to help you work out all the connections.

When we did ours I put in a 8 circuit fuse array as well as relays. It was never going to be a fully restored Jeep back to original so we used modern connectors and techniques. Been rock solid since we built it. Was significantly less than any of the prebuilt harnesses.


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