Early Cowl Battery Box Circuit Breakers

RonD2 · Post by **RonD2** » Sun Jan 23, 2022 8:54 am

Don,
The CB's are wired in parallel.
Meaning, it makes sense that the "line side" that feeds power to all three is 12 gauge.
And it makes sense that the "load side" supplying power from each to their three individual circuits are 14 gauge.

Naugha · Post by **Naugha** » Sun Jan 23, 2022 9:38 am

In addition to some NOS wiring harness sections from other jeeps, I bought 25’ of Prestolite #14 wire (cheap) to practice crimping and maybe help construct short runs of the harness.

The AWG #12 Prestolite I found on line comes in 50-100 ft. rolls and is pricy. I can buy generic unmarked #12 wire at TrueValue that has about the same diameter as the #12 Prestolite. (approx. .235”)

My measurements are approximate because when I put the micrometer on stranded wire .... well, you know.... (+/-) .01” readings.

So... are short runs of TrueValue AWG #12 likely fine for a M38 ??
Will I encounter long runs of #12 ??

I have not yet closely examined my NOS harness sections to check wire size and condition.

RonD2 · Post by **RonD2** » Sun Jan 23, 2022 10:45 am

Don,
I don't know what Tru-Value sells. There's a lot of wire on the market for all kinds of applications. You shouldn't use some generic application wire. Automotive grade wire is what you need and I recommend that's all you use.

I would've thought you'd stick with the originality of the military Prestolite for the M38? It's great stuff, meets-exceeds any automotive spec.
We're fortunate to have sources for fresh Prestolite stock (not NOS), so there's no doubt about quality. I use it on mine. Don't want to burn the house down.

You can always sell what you don't need?

Naugha · Post by **Naugha** » Sun Jan 23, 2022 12:51 pm

OK. Prestolite for the #12 wire.

I will look through my NOS harness sections, see what I have, figure out how much Presto #12 to buy and find a source that sells it in amounts closer to my need.

4x4M38 · Post by **4x4M38** » Mon Jan 24, 2022 6:57 am

Don,
Take a look at page 5 of 95, in Wes’ Photo Gallery:
M38 Electrical.

The third breaker is for the firewall mounted Auxiliary Power Receptacle.

Under sub album Harness you will find the information on converting an M35 harness to M38.

Naugha · Post by **Naugha** » Mon Jan 24, 2022 9:17 pm

Thanks Brian. I dig through the albums but am always finding new stuff or re-finding stuff.

A barn full of parts are ready to go as soon as my engine returns from the shop, which in now officially a PITA issue.

With electrical components in place ... headlights, rear lights, starter, generator, VR, body/firewall ..... there will be targets for the wiring effort.

I will study the diagrams & album pics.

Naugha · Post by **Naugha** » Tue Jan 25, 2022 2:39 pm

I cleaned up the three 15amp CB take offs, cobbled together a set of Doug connectors and went down to the classic alt/gen/electric shop to see if the old CBs could be tested..... just something I wanted to do. The owner said they did not have equipment to do that. Oh, well. Even if the old units survived a test cycle or two their age alone would be a rejection point.

The good news is that when it comes to Douglas connectors I can roll my own. Time to move on to other electrical stuff.