Headlight Control Switch Question

HBarn752 · Post by **HBarn752** » Mon Jul 22, 2013 6:47 pm

I'm currently in the process of completely re-doing my M38's electrical system. It currently does not have a headlight control switch with the three levers. Instead, it has a push/pull knob for the headlights only. The electrical system has already been converted to a 12 volt system.

If I buy the old headlight control switch, will it work on the 12 volt system? I am also planning on installing Tail/Service/Brake Lights along with the marker lights in the grill.

In addition, does anybody have a wiring diagram that corresponds to a single battery/alternator/12 volt set-up? Any help would be great.

Jim · Post by **Jim** » Mon Jul 22, 2013 7:58 pm

The military light control combo switch will work on 12 volts.
It is a simple contact, either ON or OFF, except for the panel
lights, which have a dimming feature. That should not be a
problem, but if it is, someone will have a work-around I'm sure.

Jim in Darkest Arkansas

Post by **wesk** » Mon Jul 22, 2013 8:42 pm

There are two items inside the modern M series light switches that will not function correctly with 12 volts. The built in circuit breaker and the dimming resistor. The work around would be replacing them with an appropriately rated 12 volt circuit breaker and resistor. To do this you will have to analyse and tally up all your lighting electrical loads, determine correct wire sizes and then determine the correct amperage circuit breaker and the correct resistance resistor.

The main problem with these M series light switches is they are designed as throwaways and have no published service or parts data for them. Most have crimped bodies so the challenge starts with the attempt to enter the switch.

If you are having a 12 volt civvy harnessed M38 then why even fool with the three lever switch idea?

BullRun · Post by **BullRun** » Mon Jul 22, 2013 8:43 pm

I am redoing my M38's electrical system too. The thing I have found is that the military connectors are a bit of a problem. Not in themselves but in getting bits and pieces of 24 volt and 12 volt parts to connect together.

Walck's has some really nice cloth loom CJ3A wiring harness's if you go the civi route. The harness's can be custom made too if you want for under about $300.

Post by **wesk** » Mon Jul 22, 2013 10:00 pm

There are several good technical sites that offer plans for converting to 12 volt and doing your own wiring.

Novak is one good one:

http://www.novak-adapt.com/knowledge/12_volt.htm

The Painless web site offers a lot of info:
http://www.painlessperformance.com/wiring.php
http://www.painlessperformance.com/Manuals/10105.pdf

Their CJ harness is $578

HBarn752 · Post by **HBarn752** » Mon Jul 22, 2013 11:10 pm

Great info! I really appreciate all of the help. The reason I'd like to install the three lever headlight control switch is to keep the Jeep in as much of a military appearance/operation as I can. When I bought it, it had already had the 12v system installed along with a Kaiser Supersonic engine. The oil filter and air cleaner assembly are long gone. On my current budget I'll never be able to get it back to a full mil-spec condition, but I'd like to do whatever my budget allows. For now I'm focusing on the instrument panel and lighting.

Since I can't buy a complete harness, the next problem is figuring out the receptacles of the switch and which wire goes to which light. It looks like I'll also have to locate a plug from which I can splice individual wires. Any thoughts on where I can pick up just the plug? I've looked on AJP, Kaiser, Milwest, Mullins, and Rapco....no luck. I was able to find an old M38 harness from the Greek military on ebay. Looks like it'll fit the headlight control switch with the single receptacle. Any thoughts?

Post by **wesk** » Mon Jul 22, 2013 11:19 pm

If your budget is soft then dabbling in 24V parts will eat it up quick. You should peruse my photo album where just about 80% of your questions will be answered.

http://www.willysmjeeps.com/v2/modules. ... _album.php

You are looking for what is called a "Pinout" that shows which wire numbers are attached to which pins. Look on the second page of my albums under m series lighting!

Midwest has the plugs. A lot of small general M series items are in those vendor's stockrooms and not listed on their web sites. When you don't see something listed that you need then call or email. 7 times out of 10 they'll have it.