Make it easier to trace electrical stuff.

[seattle smitty]

(Preface) (Smitty here. I am a frequent contributor to another site for owners of long-gone, orphaned cars, in this case the Dodge/Plymouth Colt Vista mini-wagon of the '80s and early '90s (http://www.coltvista.com). There was hardly any source of on-line information or sympathy for owners of these cars until last December, when Texas good-guy Alan Moore created this site. At that time, when Alan and I were just talking to each other and hoping to get our first members, Guy "89ARIES" Coulombe showed up to say hi. He also gave us a plug on these pages, which was most appreciated. We still have nothing like the membership we hope to get, but we're starting to get some action. In an effort to do something for Guy and his site, I thought maybe I could copy and paste a couple of general tech items I've written for coltvista to a tech page here. This stuff is nothing great, but it might be useful a few of your non-professional DIY-ers. And thanks again, Guy!)


(from the coltvista "General Tech, Electrical" sub-forum):

"Mitsubishikid" and I have been trying to figure out how certain things are connected by the Vista wiring harness. That should be plural, wiring harnesses, because there are several sub-harnesses. Unhandily for us, yet typically in the auto industry, each of these sub-harnesses handles multiple unrelated funtions and systems with lots of overlap between them, where we might wish for harnesses with a few discrete functions and no overlap. But the harnesses are designed mostly for ease of manufacture, so that pre-assembled and wrapped harnesses can be installed and hooked up rapidly in a car moving down the assembly line. I recognize that making everything easy to install is the only way to build a car that ordinary folk can afford to buy. But it makes life hard for the mechanic later on.

There are three aspects of wiring harnesses that I don't like, but one of them is easy to change, and one is doable with some effort:

The one that is hard to change is the overlapping functions (and the only way to fix this is to design and build your own custom wiring harness, as the most talented hot-rodders often do).

The one not quite so hard to at least partly change is the plastic connectors (designed to snap together in an instant on the assembly line, but not so easy to trace problems though)(at least the Mitsu connectors are not so hard to separate as Ford connectors, which can drive me into a killing rage). In the days before plastic wire connectors, wires which needed a disconnect point were routed to terminal blocks. A terminal block is a wiring junction with two parallel rows of screws which attach terminals soldered or crimped to the ends of wires. For example, suppose you have a blue wire coming out of a water temperature sending unit on the engine, that has to go through the firewall to an idiot-light on the dash. You might not want the wire to go all the way with out a break because it sure would make it hard to build the car. So you have a blue wire coming from the idiot light and through the firewall, and you have a blue wire coming up from the sending unit to the firewall, and attached to the firewall you had a terminal block to which you screwed the ends of the two blue wires directly across from each other (or atop each other, depending on how the terminal block completed the electrical circuit.

Terminal blocks disappeared because plastic snap-connectors are far quicker to assemble, but boy-oh-boy they were great for tracing electrical problems!! Disconnect the wire coming in from a suspected faulty component, and see what happens. Or disconnect to check voltage (if any, how much?). And it's all right there high on the firewall, easy to find, easy to get at with your test probes. It was such a superior arrangement (for everybody but the car-builder) that on my '79 Ford van I fabricated a big panel of 1/4" thick clear plastic and mounted six terminal blocks, each with ten pairs of connecting points, and ran every wire to them from the huge wire bundle that goes from the engine bay through the firewall and behind the dash. I can see all the wire colors, refer to the wiring diagrams to see what they operate, and do a lot of trouble-shooting right there. It was some effort, but my mechanical buddies think it's awesome.

And it relates to the third thing about factory wiring that I dislike, CAN'T STAND!!, and that is loom-tape. Loom-tape is black plastic tape that looks just like electrical tape but has no stickum. When wiring harnesses are made up at the factory, before they are installed in the car, groups of wires that will go in the same area of the car are wrapped in loom tape to hold them together (to keep it from unraveling, the very ends of the loom tape are secured by a bit of electrial tape). Thus, as a car coming down the assembly line gets to the harness installer, he can grab an assembled harness off the pile and quickly place all of the taped sections where they belong and then snap the plastic connectors together. Bang, bang, bang, real fast and efficient . . . for the factory, NOT the mechanic! That damned loom tape makes it a real chore to find particular wires. You're bent over the fender, or upside down under the dash, looking at the tiny portion of exposed wiring entering a connector that's just beyond where your eyes focus, trying to hold a penlight in one hand and peel the tape back enough so that you can try to make out the faded wire and tracer colors . . .ARRRGGGHHHH!!!!

My answer, and I'm making this a suggestion for any owner: GET RID OF THE LOOM-TAPE!! Strip it all completely off your wiring (and throw it into a big pile and photograph it, which is what I did in the case of my Vista! ). I got rid of all of those plastic wire bundlers, too, those corrugated pieces of flexible tubing that are slit so you can slip them on and off the wire bundles; they are less trouble to deal with than loom-tape, but they still get in my way. To keep everything looking neat and organized, I replace the loom-tape and plastic tube with those little bitty black zip-ties, about 6" apart, "zipped" slightly loosely. Now it all looks just as neat as before, yet at any place on the harness I can EASILY look at wire colors, and I can EASILY. see where a particular wire leaves the bundle to go to a component, which was damned difficult previously. If I can't get a look at a particular wire in the middle of a big bundle, in seconds I can snip off a couple of my little zip-ties (I always have extras handy) and spread out the wires.

This looks just as good as before, the wires might stay a little cooler (a possible added benefit in a few cases), and some of the worst hassle of automotive electrical work is eliminated. If you do this work yourself, you'll like it. If you pay a mechanic, he'll love it, and finish his work sooner.
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