Engine wiring harness NIGHTMARE

Hey guys, as I alluded to in an earlier thread, my friend and I are going to drop a wideblock 4g63 and a Starion tranny into his '83 RX7. It was going to get a V8, but for some reason he had a change of heart not long ago. Well, after parting two cars I have just about everything we need to do the swap, except of course the Starion tranny, wideblock engine block, and some various other things. I'll make a thread on it later when we get to be more for sure on the specifics.

When it actually came time to wire it I was going to remove the old plugs that I wouldnt need anymore, as well as make sure the old splicings were solid. Well, I started into it tonight and I found out that its a complete fuck job. Someone has been through this before and the words "soldering iron" and "quality workmanship" didnt mean a damn thing.

Well, I sort of plan on going through it completely so we're 100% sure it works right. Anyone have any intimate experience with a wiring harness, specifically rebuilding one? What about websites anyone know about any good wiring references? I have a couple, but others wouldnt hurt. I'll post pics of the damage later.

Wow that sounds like a mess. Just be care full and make sure it right when you get done. It would be a PITA to have to track the problem down and fix it with it in the car.

I don't really get what you're asking....are you asking if they make a book or soemthing about engine wiring? As far as I'm concerned, rebuilding a wiring harness has more to do with hands-on experience than reading something in a book. I had to completely re-do the entire engine bay harness in my RS and it took about 3 hours from start to finish.

What I would do is take it into a big area, sprawl it out all over the floor (not in a big messy bundle) and then cut off all of the wire loom. That way you'll be able to see all the trouble spots and shit like that. Then just follow all the wires, replacing the necessary stuff, until you're done.

If you need to add wire to make a sensor longer, use THHN/THWN wire as it is gasoline and oil resistant.

Well, I think we got ahead of ourselves on this one. I would absolutely love to do the project, but I kind of cant see it happening anymore. First off, my buddy and his girlfriend are expecting around Thanksgiving. Right now he's got two FB RX-7's (the one thats torn down that was going to get the 4g63 and an absolulte peach of a '85 GSL-SE) but he also wants an econo car for when the baby comes. Two project cars, a DD, and a kid dont mix anyway you spin it. I can understand him wanting a 4 door DD for hauling the kid around and shit and keeping the GSL-SE since it is in such great shape, but dumping several grand into the other one right before the kid comes is a terrible idea.

Garrett, I guess I was looking for a good wiring diagram of the harness or a schematic or something. I guess I dont need one as much as I thought, it seems to be a pretty straight forward operation. Since its not (or atleast shouldnt) go in my buddy's car I want to sell it, but theres no way in hell I will let something like that leave here in that kind of shape. I think I am still going to go through it and fix its cobble jobs then sell it later. Anyone have any idea where to get that kind of wire? I dont think I've ever run across it...

Any electrical place will know what you are talking about. Maybe even home depot.

I used to build wiring harness's for aircraft. It's similar if not almost exactly the same. What do you need help with? It's pretty much swaping it out wire for wire. If you have to splice, make sure you stagger the splices in the lines.

If you want to completely replace all the wiring and you have no schematic. Just do it one wire at a time, assuming you are going to use the same plugs and crap from the original harness. I have wiring schematics of 1g eclipses, is that what you are looking for?

Also what is so wrong with the harness you have? I may be able to give better tips with more detail.

Yeah, I think I will just do it one at a time... maybe do a detailed write up on it and what wires go to what. I can take pics of it later once I get done icing my leg, but its pretty cobbled up. The only thing is I dont want to have to buy a gang of different colored wire, and it might be kinda bad looking at a wiring harness that half of everything is the same color, but atleast it will be in good working order right?

Yeah, I think I will just do it one at a time... maybe do a detailed write up on it and what wires go to what. I can take pics of it later once I get done icing my leg, but its pretty cobbled up. The only thing is I dont want to have to buy a gang of different colored wire, and it might be kinda bad looking at a wiring harness that half of everything is the same color, but atleast it will be in good working order right?


Color doesn't mean anything. That is just for the end user or mechanic to make wire identification easier. Hell there is like 1000X more wiring on a helio and though it is different guages, all of it is white and looks exactly the same.

Just buy some wiring and do it up. Don't worry about color coding it. If you want to label it, use tape and some markers and wrap a piece of tape at each end and mark it with a color.

I mean, I think most of the connectors/plugs are non-solder type, so you should be able to swap them out. I think I remember you telling me you know how to solder, so if there are any do it up. Just make sure to take your time and not rush. Do one at a time, last thing you want to do is have to shoot a harness looking for a crossed wire.

Other than that, I don't think there is anything you will have problems with. Wiring harnesses are pretty much just repetitive action. Some of the ones on the aircraft used to take me WEEKS to wire up. Then again we are talking about plugs having a few hundred wires running to them.

Hey guys, as I alluded to in an earlier thread, my friend and I are going to drop a wideblock 4g63 and a Starion tranny into his '83 RX7. It was going to get a V8, but for some reason he had a change of heart not long ago. Well, after parting two cars I have just about everything we need to do the swap, except of course the Starion tranny, wideblock engine block, and some various other things. I'll make a thread on it later when we get to be more for sure on the specifics.

When it actually came time to wire it I was going to remove the old plugs that I wouldnt need anymore, as well as make sure the old splicings were solid. Well, I started into it tonight and I found out that its a complete fuck job. Someone has been through this before and the words "soldering iron" and "quality workmanship" didnt mean a damn thing.

Well, I sort of plan on going through it completely so we're 100% sure it works right. Anyone have any intimate experience with a wiring harness, specifically rebuilding one? What about websites anyone know about any good wiring references? I have a couple, but others wouldnt hurt. I'll post pics of the damage later.


My buddy has a starion 5 speed in his shop collecting dust =P

Hope this swap gets some priority.

The RWD has a semi/custom harness, and I need to start building another one for the MM, so I'm balls deep in this. One 1g and one 2g, of course, just to make things dificult. :D I may try to take some notes to help you out if you still need it, but my days of long writeups with all the details are over. Having 3 DSMs is killing me. :D

I was wrong in my post, you want MTW(machine tool wire). Not THHN. It's dull unlinke the shiny THHN. Was high on something here at work...