12v wiring harness

southpw · Post by **southpw** » Sat Sep 19, 2015 8:59 am

I'm trying to determine if a 12 curcuit wiring harness will be enough for my M38. I am counting the different things I will need power to but worry I forget something and the harness I buy will be inadequate.
Lights
ignition
turn signals
brake lights
dash lights
alternator
fuel
what am I missing?
And has anyone had any experience with some of these cheaper wiring harnesses? I was going to buy the 20 curcuit harness from Speedway but they discontinued it so now they only have the 12 curcuit available for a short time.
Thanks

southpw · Post by **southpw** » Sat Sep 19, 2015 9:06 am

This is the harness I'm looking at now. Am Iasking for trouble by not buying a name brand like Painless?

http://m.ebay.ca/itm/131596494525?ul_re ... mwBanner=1

Post by **wesk** » Sat Sep 19, 2015 12:00 pm

You will always get what you pay for. Buying cheap rarely guarantees a speedy and successful project.

Also be specific in your questions. For example, are you trying to substitute a cheap aftermarket harness for use with a stock 24 volt jeep? Or are you trying to convert your jeep to 12 volt? If you are trying to convert then to answer your question we would need to know or see a list of all electrical components installed on your jeep. Also any peculiar wiring needs of each component.

southpw · Post by **southpw** » Sat Sep 19, 2015 1:29 pm

Thanks Wes. My M38 will be converted to 12v and have the alternator and 12v headlights already. I will be adding turn signals and using new gauges where needed. I'm hoping to keep original speedometer and hope the mechanic will safety the Jeep even though there is no illumination.
I will not be adding any other electrical accessories to my project.

I see Walck's has some wiring harnesses for the 3A. One of those with turn key and turn signals would probably work well considering how similar the vehicles are.

Post by **wesk** » Sat Sep 19, 2015 6:48 pm

When converting to 12 V civvy use the CJ5 wiring harness.

groundhog · Post by **groundhog** » Fri Oct 02, 2015 6:18 am

What if I do not have a wiring harness for my M38 rebuild, and I do not want to go to 24 volt. If I go with 12 volt, would I still buy a CJ5 harness, and would I have to request any custom changes? Should I convert my generator and starter, or is there a better way to go with those? Thanks
Ron K, Lakeview, MI

Post by **wesk** » Fri Oct 02, 2015 7:19 am

12V means everything must be 12 V.

24V means everything must be 24 volt.

If electrical work is not your best suit then it is one place you can cause yourself a lot of grief if you don't hire knowledgeable help. Trying to learn all about electrical systems and wiring harnesses on a web site takes many hours and is one of the worse places to learn since you will get help (Both qualified and un-qualified) from many folks all wishing to do well by you.

Most folks not well versed in auto electrical are intimidated by 24 volt systems. This is what drives them to 12 volt conversions. Staying with the stock 24 volt would have been easier then attempting the conversion for these folks.

When folks still insist on converting the next safest thing to do is hire it out. If that's not an option then the next step is to by a harness built as a conversion harness. These cost a wee bit more but they come with detailed instructions to move you right along.

Using a stock CJ5 12 volt harness makes life much easier. The cable lengths will already be correct. You buy a CJ5 round instrument cluster, light switch, and ignition switch then switch all 24 volt specific components with stock CJ5 specific components.

If one goes about this half-arsed then the final product will be half-arsed and either brake down on you a lot or catch fire one day.

32sbct · Post by **32sbct** » Fri Oct 23, 2015 6:27 pm

I purchased a 3A 12 volt wiring harness for my M38 from Walck's. I had them add provisions for turn signals and a key start. I have not installed it yet so I can't give it a 100 % endorsement but it looks very well made. The jeep had no wiring harness and the only parts of the electrical system I had were a 6 volt starter and generator that I had rebuilt to 12 volt. I am also missing the engine compartment battery box and bracket which was cut off with a torch at some point in its past. Trying to return to the original 24 volt system was just too expensive for me to tackle.

southpw · Post by **southpw** » Fri Oct 23, 2015 8:24 pm

32sbct wrote:I purchased a 3A 12 volt wiring harness for my M38 from Walck's. I had them add provisions for turn signals and a key start. I have not installed it yet so I can't give it a 100 % endorsement but it looks very well made. The jeep had no wiring harness and the only parts of the electrical system I had were a 6 volt starter and generator that I had rebuilt to 12 volt. I am also missing the engine compartment battery box and bracket which was cut off with a torch at some point in its past. Trying to return to the original 24 volt system was just too expensive for me to tackle.

That is the same harness I'm thinking about. Please update with your thoughts as I'm not close to that point in my project.