Gearhead_42
Gearhead_42 Dork
1/19/21 7:53 p.m.

Any have anything good to say about a wiring harness builder?  All I can find are horror stories about non delivery, bad pinouts, crappy tunes... 

 

Swapping LE5 into my S13, and after doing way too many of my own harnesses I just wanted to push the easy button for once.  

Slippery (Forum Supporter)
Slippery (Forum Supporter) UltraDork
1/19/21 8:10 p.m.
Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
1/20/21 8:56 a.m.

You get what you pay for (or want to pay for).

I won't even consider to build a custom harness if it's under 2k in labor and materials. Modifying stock harnesses can be even worse as you never know the condition of the donors and may have to "fix" things that should have been "easy" and you're too deep in to recover. I make some PnP harness adapters as well but I have done a lot of them and use all new parts so it's easy and a good value. The amount of time just planning is quite considerable, and if you have done it before, you know this.

Duke
Duke MegaDork
1/20/21 9:01 a.m.
Tyler H (Forum Supporter)
Tyler H (Forum Supporter) UberDork
1/20/21 9:27 a.m.

I have done my own harnesses because I have to do my own troubleshooting.  I hate it.  I earned the dubious reputation of being capable, so now I'm the go-to for all our Lemons and Chumpcar needs.  (I hate it.)

I would gladly pay good money for a harness if one is readily available and proven for my project application.  But I would already have my wiring figured out and tone out every wire in the harness and verify it.  

Just buying a harness to bypass understanding how it works scares me for all of the reasons cited in post #1.

pirate
pirate HalfDork
1/20/21 9:42 a.m.

I'll second Ron Francis Wiring. When I was building a car I called them and they were easy to talk too and offered advice on what I would probably need. Each harness they sell has a serial number so if you have questions they know exactly what they built for you. After buying harness they were very helpful when I run into a problem from my own doing. They use top quality wire, connectors, wires are color coded and labeled. I had never wired a whole car and the task seemed daunting but all turned out well. They won't be the least expensive but in this case I thing you get what you pay for.

I used a Swap Specialties harness in the Lemons B210 with a LE5. Told him what I had and what I was doing with it. He built a harness to fit that came with a fuse box, fan and fuel pump relays.  I was happy with how it worked. 

https://swapspecialties.com/

MadScientistMatt
MadScientistMatt UltimaDork
1/20/21 9:54 a.m.

It's tough to find one that will do quality work at a good price, and for something as odd as an Ecotec swapped Nissan, it's probably best to bring it to a shop rather than trusting someone to have a good off the shelf solution.

Good wiring harness suppliers are hard to find. When we rolled out LS drop on harnesses, we tried to work with a couple existing LS harness builders who shall remain nameless, to see if somebody could just build their existing harnesses with an MS3Pro ECU connector instead of the stock one. Some just never returned our messages. One built a pretty good prototype and then disappeared when we tried to order more. Others delivered questionable build quality with pins that fell out or strange routing choices.

In the end, we wound up drawing up our own blueprints and taking them to a contract manufacturer. Even then, we've had to change suppliers once so far when some scheduling issues cropped up.

Keith Tanner
Keith Tanner MegaDork
1/20/21 9:57 a.m.
Paul_VR6 (Forum Supporter) said:

You get what you pay for (or want to pay for).

I won't even consider to build a custom harness if it's under 2k in labor and materials. Modifying stock harnesses can be even worse as you never know the condition of the donors and may have to "fix" things that should have been "easy" and you're too deep in to recover. I make some PnP harness adapters as well but I have done a lot of them and use all new parts so it's easy and a good value. The amount of time just planning is quite considerable, and if you have done it before, you know this.

100%. It's labor intensive detail oriented work with materials that are surprisingly expensive when you add them all up. So it costs real money to get it done well.

I've built harnesses from scratch as well as modified stock ones and I have to say that they're not that much different in the level of effort. The nice thing about using a modified stock harness is that you can continue to use factory wiring diagrams and wire colors and the wire quality tends to be quite good, but you are not immune from the problems of age.

engiekev
engiekev HalfDork
1/20/21 10:05 a.m.
Keith Tanner said:
Paul_VR6 (Forum Supporter) said:

You get what you pay for (or want to pay for).

I won't even consider to build a custom harness if it's under 2k in labor and materials. Modifying stock harnesses can be even worse as you never know the condition of the donors and may have to "fix" things that should have been "easy" and you're too deep in to recover. I make some PnP harness adapters as well but I have done a lot of them and use all new parts so it's easy and a good value. The amount of time just planning is quite considerable, and if you have done it before, you know this.

100%. It's labor intensive detail oriented work with materials that are surprisingly expensive when you add them all up. So it costs real money to get it done well.

I've built harnesses from scratch as well as modified stock ones and I have to say that they're not that much different in the level of effort. The nice thing about using a modified stock harness is that you can continue to use factory wiring diagrams and wire colors and the wire quality tends to be quite good, but you are not immune from the problems of age.

With modifying stock harnesses, age is a big issue certainly.  Depending on the environment the vehicle was in, the wires themselves will have brittle insulation, corroded strands, and could have shorts.  Another component that has an age limit, or use limit, are the factory connectors.  The factory connectors are not meant to be disconnected/connected many times, the pins and terminals wear and the connection will be compromised.  Even if the connectors werent disconnected/connected, there are fatigue limits with any connector since vibration can cause fretting on the terminal/pin surface. Ideally on a modified stock harness one would go through and replace all the factory connector terminals, if the wiring itself is still in serviceable shape.  

A fresh aftermarket harness from a reputable shop is well worth the cash, compared to DNF'ing an event due to wiring issues on a crusty stock harness or poorly built aftermarket harness. This is especially more true on older vehicles without modern OBD, turns out all the DTCs for wiring on newer vehicles are actually very useful in tracking down wiring issues!

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
1/20/21 10:41 a.m.

Agreed even if I use some stock bits I try and repin everything if that is available (though pins get spendy!). I have found that German harnesses generally are pretty age-proof compared to some US and Japanese ones. I am not sure if British cars use wires, and if they do, I would avoid that.

infernosg
infernosg Reader
1/20/21 11:03 a.m.

I had the engine harness for my RX7 built by Chris Ludwig at LMS-EFI. I'm pretty sure it was the second, single most expensive purchase for the car.  I was planning on doing it myself but was going crazy trying to source all the different wire sizes, connectors, pins, etc. Plus, a lot of that stuff comes in bulk, which just isn't convenient or cost effective for many people. I kept and modified the chassis harness myself, which mainly involved removing lots of wire and de-pinning lots of connectors. Since most of those wires and connectors are inside the car they're in good shape despite being 35 years old. Being able to still reference the factory wiring diagram is a major plus.

kb58
kb58 SuperDork
1/20/21 11:16 a.m.

Somewhere I have a link to a REAL harness manufacturer, and their automotive products are indistinguishable from military quality. They're used on high-end pro cars, including F1. If paying $$$$ (or even $$$$$) for a harness isn't a problem, there you go!

Keith Tanner
Keith Tanner MegaDork
1/20/21 12:26 p.m.
Paul_VR6 (Forum Supporter) said:

Agreed even if I use some stock bits I try and repin everything if that is available (though pins get spendy!). I have found that German harnesses generally are pretty age-proof compared to some US and Japanese ones. I am not sure if British cars use wires, and if they do, I would avoid that.

Surprisingly, the wiring harness in my 1972 MG is in remarkably good condition. At least the wires are. The bullet connectors seem pretty solid if you clean them. Granted, that's not a competition car but of the problems it has had, the wiring is not it. Miata wiring lasts pretty well, the biggest age-related problem I've noted has been corrosion in the big primary battery cable that runs the length of the car. Also, there was one poorly supported wire bundle running to the cam angle sensor on the NA that could break internally. Problems with the stuff plugged into the wiring harness, well, yes.

Meanwhile, my 20 year old Jeep started having spontaneous wiring problems about 5 years ago.

DirtyBird222
DirtyBird222 PowerDork
1/20/21 3:12 p.m.
Slippery (Forum Supporter) said:

Rywire

Rywire builds a great harness; however, their customer service is straight up trash. 

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