This is my thread about wiring up my GTX car:
This is my thread about wiring my GTX car. I can't think of too many topics more boring to start a thread about than this. Also, there will be very little info of benefit to owners of typical Opels because this car has almost none of the original parts, systems, and wiring. These changes to the...
It was the first time I had rewired a car and a car that had a custom dash and switches and an electronic instrument cluster with a controller, plus all sorts of special gadgets like power steering and stuff. Most of the stuff I did was a good idea and some were good, but could have been a lot better. I'm trying to do the "better" part this time around. I worked with Post Office letter and package processing machines for 30 years and they had miles of wiring and 100's/1000's of parts and devices, motors, circuit boards, controllers, interfaces, etc. I don't consider myself to be a "car guy", I'm a "machine guy" who happens to like to fix up Opel GT's. Cars, by their nature, wire things up with a lot of "shared circuits" and local grounds to the body. Multiple devices share one fuse and many devices ground through themselves to the body or a short wire. I don't like that, that's not what I'm used to. Dozens of local grounds can cause dozens of poorly grounded devices. Circuit or fuse sharing can cause trouble. Harness connectors, as previously stated, can cause problems. In my "Gordo Wires..." thread I drew up individual circuit diagrams for subfunctions that needed to be documented because I did them in a unique way or because they were complicated. My turn signal and flasher wiring is unique, I didn't know how to stop feedback from making ALL the lights flash when I activated the turn signal, so I used diodes to isolate the circuits to prevent this, as shown here:
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The oem turn signal/flasher/headlight relay is almost incomprehensible, to most people, including me. Morphing that into my aftermarket fuse box that had separate flasher and turn signal relays hurt my brain. The oem relay also has that German car function that let's you leave a turn signal light on all night long. No way did I want or want to figure out how to blend that into the system, so I kept it simple.
To answer Wilderbry's sort of question: It was simply better for me to use an aftermarket fuse box with all new wiring and electrical contacts and lots of individual circuits, plus no harness coonctors throwing a wrench and complexity into the mix. I know exactly how each circuit is wired. Each wire is already labeled to tell you what function it serves and the color coding is standard GM style. I could theoretically give my car to a repair shop and they could understand the wiring based on the color coding alone.
I bought the 28 circuit "Classic Customizable Trunk Mount Chassis Harness" from Painless performance because it was guaranteed to have wires that were long enough to reach every conceivable device and location I had. I paid the big bucks for the "10220" version because I didn't want to get screwed like I did the first time around with a whole bunch of wires that were too short. There's no point in having nice color coded and labeled wires if you have to extend with butt connectors a whole bunch of important ones with generic red and black wire from the auto store in all the wrong gages. Having lots of labeled fuses means I can put virtually everything on one dedicated circuit that's easy to find the fuse for. And there's extra unused wires for devices that I could add at a later date. :
It also totally sucks to entertain the thought of rewiring a car with a fuse box under and behind the dash where every maneuver is a royal PIA. Most of us are old guys with poor vision, bad backs and knees, and bloated bellies, why make rewiring a PIA when you can just put it behind the seats and everything is easily visible and accessible? But I had to pay extra for that convenience with the extra long wires. A similar Painless system for under the dash is almost half the price, but, trust me, you'll be cursing your face off for not dropping the extra couple of hundred dollars for the trunk mount version with the long wires. What is your time, convenience, and enjoyment of the job worth? To me, spending a few hundred extra dollars for extra long wires and have the extra convenience and sanity will be worth every penny. And, on the plus side, I'll have PLENTY of extra color coded and labeled wire for future situations. That said, if you're cost challenged and really enjoy pains in your azz, you could buy this kit or a similar one. This is the under the dash version: