Photography by Carl Heideman
In the hierarchy of automotive dreads, rust repair and wiring rank near the top for most people. Rust repair we get, but wiring doesn’t have to be a nightmare. After all, a wire just goes from one place to another. How hard can that be?
The problem is there’s always more than one wire. And those wires connect to things. And terminals are often of poor quality or improperly used. Then, all those wires and terminals get put in a bundle. And that bundle is usually made very haphazardly. And it looks like a mess. Because it is a mess. Fear and dread: validated.
But it doesn’t have to be that way. If wiring is done neatly, using quality terminals and correct crimping, the work can be satisfying and will rarely fail beyond wear in switches, relays, motors and other components. And if it’s done with servicing these components in mind, repairs are very quick.
We recently rewired a Factory Five Type 65Coupe. The car was built more than 10 years ago and was equipped with an American Autowire universal wiring harness kit. The installation was beyond sloppy, and the car had experienced typical gremlins and poor-quality “repairs” ever since.
Each “repair” was treating a symptom instead of curing the core lack of neatness and quality connections, so we pulled everything apart and basically started over. We were able to save the harness as we did this. (By the way, Factory Five now offers purpose-designed wiring for its cars, so the company has made it easier to avoid these types of problems.)
Follow along as we turn a mess into a tidy, dependable and serviceable wiring harness that won’t inspire fear in the next person to work on it. In future installments, we’ll cover more about the tools, terminals and techniques for wiring success. We’ll also teach you how to build a harness from scratch–with and without a kit. Stick with us, and you’ll be able to remove wiring from your own hierarchy of automotive dreads.
1. When we pulled the dashboard out of this Factory Five Coupe, we found a typical wiring mess: wires of all colors and lengths, some up to 6 feet too long, plus relays that couldn’t be serviced without removing the dashboard. Terminals ranged from quality and properly installed to tape and wire nuts. Overheated and partially melted wires and terminals had simply been left in place. We had a lot of work to do.
2. After spending a little time trying to remedy things in situ, we realized we’d save time by removing the fuse box and main dashboard harness from the car. We labeled and photographed everything before pulling it out so we had good references for later.
The easiest way to make wiring serviceable is to untangle the mess and neaten everything. Our neatness rules include not crossing wires; keeping appropriate wires bundled together, often in subbundles; and keeping lengths exactly appropriate. This neatness takes time.
3, 4. Along the way, we found some wires tangled right at their multi-wire connectors. We de-pinned those connectors and organized the wires, making sure to keep them in the right place and not cross them. In this case, we used some temporary zip-ties to keep the bundle neat.
5. Some of our multi-wire connectors had melted. Fortunately, American Autowire sells replacements, so we reterminated the wires and then neatly inserted them.
6. At this point, we had the harness roughed out. We used more temporary zip-ties to keep the subbundles organized. We could then reinstall the fuse box and harness and work on routing and neatening the subbundles.
7. Dealing with 15 to 20 circuits and a lot of colors can be overwhelming. The American Autowire harness had printed circuit names on the wires, so that made the job easier for us (and less reliant on a wiring diagram). Where we needed more information, we got out the tape and Sharpie to label things.
8. We then neatened each subbundle. After determining appropriate lengths and reterminating wires as necessary, we neatly held together the wires in the subbundle with zip-ties, making sure they didn’t cross each other. This is part of our method for simplifying future service, as any wire can be easily seen and traced. If, for some reason, a wire needs to be removed or added, it can be done without disturbing the rest of the bundle.
Finally, we routed the wires along appropriate paths and attached them to the supporting structure. Note that we use zip-ties to bundle wires or attach those bundles to supporting structure, but never both at once. This allows us to pull a subbundle from its supporting structure for service without messing up the bundle.
9. As we assembled each subbundle, we did our best to test our work. We’d generally attach a fused power source to the subbundle and then determine that the component was working properly. If we couldn’t test the component, we’d use a multimeter or test light to make sure polarity and continuity were appropriate.
[How to solve common electrical issues with only a test light]
10, 11. Unsupported multi-pin connectors are a pretty big sin: They’re relatively heavy and sooner or later tend to shake themselves loose, even with quality snap connections. So we strive to attach and support them to some structure. In this case, we made some brackets to zip-tie them in place. We were careful to locate the connectors and brackets in a place where they could be reached with the dash in place for future service and repair.
12, 13. These relays were previously installed in a place completely unreachable with the dash installed. Since relays fail from time to time and need to be serviced, we relocated them within easy reach. We also converted their connections from four individual wires and terminals to four terminal multi-connectors sourced from Terminal Supply. Finally, we labeled them.
14. Several hours later, the dash wiring was starting to look reasonably neat. Almost all the zip-ties in the picture are still temporary. Several times, we found ourselves adding or rerouting wires in the big bundle as we cleaned up subbundles or relocated components.
15, 16. The subbundles behind the gauges didn’t start as such a mess, but we were still able to clean them up a bit.
17. We finally had a dashboard harness that wasn’t frightening. We put the final set of zip-ties around the bundles and strapped the bundles to their supports before installing the dashboard and doing one last test.
Proper tools make for a proper job. Our four go-to tools for wiring: two types of automatic strippers, a generic crimper for more generic terminals, and a specialty crimper for some specialty terminals.
Everyone has an opinion about terminals, and you’ll hear more from us later as we dive even deeper into wiring. For now, we’ll show you the high-quality bare terminals we like. We insulate them with heat shrink tubing. We’ve put together this kit from the Terminal Supply catalog.
YOU CAN DO BETTER THAN THIS!
[narrator, watching me do wiring]: It turns out, he could not do any better than this.
Both timely and appropriate as I prepare to make better the American Autowire harness in my own Type65.
Looking forward to the future installments, and thank you for sharing your knowledge and experience
JG Pasterjak said:YOU CAN DO BETTER THAN THIS!
[narrator, watching me do wiring]: It turns out, he could not do any better than this.
Thus the current Colin conundrum. I want to do better than this. It requires a crazy amount of planning, because wiring harnesses look like that when things are added after-the-fact.
I would welcome some tips on thining out thee harness of my e36 track car, just want push button start, brake lights, fuel pump etc.... thanks in advance, the
In reply to The :
The slow but sure way I have been doing it: Identify a connector you do not need, cut the connector off of the wires, remove the loom (if it is like the R53, the loom is cloth tape wrappings) and resecure the harness with a few zipties at strategic points, extract the wiring from the loom by PUSHING to find where it wiggles. Continue until you get to a splice (cut at splice), ground junction, fuse box, or wherever else it terminates.
You will need to re-snug the zip ties on occasion as you thin the herd. That is why zip ties are nice. Get big bag and be generous with their use.
Here's a pic I took while I was about a quarter of the way through my current progress. Almost all of the wires running down the tunnel area are gone except for about seven or eight, for the power mirrors. Likewise a lot of the ones on the right, quite a few on the left, and I even got it to the point where I was able to re-loom the wiring in spots.
Pete, thanks for the tip, thats kind of the way I was thinking, take out a wire, does the car still run, yes/no go or stay. thanks, the
The "physical" aspects of wiring... proper crimping, gauges, connectors, looming, routing, etc are great and this article is addressing that part of the job. Will you get into designing a wiring topography that isolates data circuits and their power supplies from the "noisy" side of the car that carries fan motors, ignition systems,e tc ? Also, proper grounding is crucial.
I bought a Panoz GTS that had been a full-time race car for about 20 years and, along the way, "Race day" repairs had been made to the wiring harness. When I pulled the dash tins off, revealing a bit of a rat's nest, my coach and friend said, "You can just put that right back and walk away", but I knew I could never unsee that. The last thing I wanted on my mind at 165 MPH entering 10a at Road Atlanta was "Man, that wiring is a mess". :-)
I rewired the entire car from the firewall to the rear bumper, removing old, broken circuits, adding a rain light, a new switch panel and all the "oddities" from two decades of repairs made under the time pressure of getting back into the race.
Proper wiring, with proper devices and materials, gives me a real peace of mind on track, plus elevates my knowledge of the car.
I have created my own mess. I wasn't happy with my FFR roadster set up as it came from Factory Five so I installed a good aftermarket generic 20 circuit harness. I'm now trying to get that looking like the pics on the boards and not having any luck. So, my fallback position is to sort bundle and remove the excess. It's this last piece that is driving me nuts. What to cut? where to cut? Should I be ruthless and eliminate wires that I could possibly need in the future... ?#*#?*!? HELP
I don't suppose you guys have the order from your "kit" from Terminal Supply sitting around as an example BOM?
We have found that if you draw out what you want on a single piece of paper, then start removing what is not need in the harness, it goes rather wekk.
YRMV
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