Thread: Making wiring harness?

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You might think about building it backwards-------like go to the farest corner(tail lite?) and wire backwards to the switch/fuse---helps sometimes in laying out the paths for the wires to look neat and effiecnt use of your material---and get some fishing line/kite string so you can tie the wires together and still be able to undo as you go----------that is if you can tie a bow!!!!!!!!!!!!!!!!!!!!!!!!!!!

I was considering working backwards, and that's probably what I will do. I'v got the Subaru fuse block almost ready to seperate the 2 halves to get to the internal wiring. I may only use the Escort fuse block as it takes std Bosch relays, but the Subaru fuse box takes non standard 4 pin relays

Originally Posted by astroracer

Hey Matt,
I doubt you will beat the price of a kit by building and buying all of the components to wire your car yourself but, if you decide to forge ahead. Look to this guy for your wire.
This is an excerpt out of my Astro build...

As I have been pulling together the wiring I have found some excellant suppliers with high quality products. The wiring books were a couple and here is another.
If anyone is in need of automotive wire give Nate Garland at Welcome to Wire Barn - Your Trusted Wire and Supply Source a look. He sells a number of different types with GXL cross-linked polyethelene being one of them. This stuff is a far cry from your basic PVC covered junk.
He sells it in 25' lengths in multi-packs of six or eight colors. This is perfect for a home builder like myself as I don't need 100' spools of wire laying around. It's also a helluva lot cheaper... I just bought 1 ea. of the 18ga, 16ga and 14ga 8 color packs from him and paid about what I would have for four 100' spools of 16ga. This is more then enough wire to finish up the van and probably a couple more projects down the road. With 8 colors and three ga sizes I am pretty well set for wire for a while. He also has 12 ga and I'll be picking up a selction of that this week.
Here are some pics of the wire he sent me. It is very nice stuff. And it is made in the USA!!!

OK I'll show my ignorance ...
Is there a chart or info of some kind that tell you what gauge wire to use on what circuits?
I'm a complete newbie to wiring.

This is out of my van thread.... Get these books and you will be well on your way.
I have done a lot of wiring before so I am very comfortable doing it. I know a lot of people are intimidated by the "spaghetti"... If you want to learn more I would suggest picking up two books. Both of them are by Tony Candela and are very well written.
He touches base on all of the basics in his first book

and covers some fairly in-depth projects in his second.

I have read through both of them a few times and everything I am doing here on the van I have either picked up through Tony's books or had my knowledge reinforced or changed for the better by him. The other thing I can tell you is, if you want to learn to do your own wiring, get out and do it. It's not that difficult and, with these books as reference, I think anybody could re-wire a car with little difficulty. Or just start small by tiding up all of those loose wires!
Thanks for looking
Mark

There is also a calculator on Project33 1933 Ford Street Rod. know the feet and the amps, and it gives you the gauge required. It basically follows the standard chart tho

Matt,
It's not rocket science, but you need to consider that you can cook a car with a botched wiring job, too, and bringing one back from an electrical fire is not a fun task. I really think that you'd find that adapting a harness from EZWire or Speedway will provide you with a lot of the enjoyment you're looking for without the risks of taking on a scratch built harness. I know for me, going through the steps of segregating the coils of pre-labeled wires into the circuits going front, rear and dash; along with considering where to allocate the two or three or four "spares" that I wasn't using was a lot more than I anticipated. Then getting the block mounted where it would be accessible for the future, but not in plain view adds to the fun. Just sayin' if you haven't done one from scratch before it could be a step toward a project stalling, or worse. Just food for thought....

But if you don't do your first one you'll never know the fun. Sure it can be a pain but it realy is not a big deal.I have never bought a KIT always wire them myself. It is not something to rush into. But its not impossible.

And as long as you use an appropriate sized fuse, all should be well.

I'll attempt to create a harness/ circuits with the fuse/ relay blocks that I have ( mounted to plywwod or something ) and if I can get it to work with a car battery, than I will use it in the hotrod, if not I will buy a kit instead of what is needed to complete a home built harness. I have an understanding of automotive electrical, can trace wires with diagrams, make repairs, and I have built lighting harnesses, just never done multiple circuits.

The link to project 33 was just a reply to above. I know how to size wire, and I usually go up ( down one gauge ) one size just because.

GM performance parts have a couple of universal wiring kits----P/N 12355693 ultimate series 18 circuit

P/N 12355691 Custom series 12 circuit

just do your circuits ONE at a time. You'll do just fine

That's actually what I was thinking... Complete one circuit and diagram at a time. Then when all is said and done, I can split loom and electrical tape the paired wires to make a 'harness.

I have decided to abandon the Subaru fuse block. For one thing it uses non standard relays but also I accidentally drove over the fuse block cover to my Subaru.. So I needed the cover from it..
The Escort fuse block mounts a little better for a custom application ( side tabs ) and uses Bosch relays anyway. So between the Marine fuse block and the Escort Fuse/ Relay block, I should have enough relays and high current fuses to make it all work.

What does the relay actually do?
Are they necessary?
Again, I'm being ignorant to electrics.

Relays control a high current circuit with a low current control circuit using an electromagnetic 'latch' which is essentially a switch itself. Headlights, electric fuel pumps and electric fans should be wired with relays..

Un-necessary post.