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the wiring sins of my forefathers


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I've had my '79 Brat for a year or so and, as you'd expect, things occasionally go wrong and then I yell at the car with a wrench and then it's okay again, generally. Right now my biggest headache is a series of minor electrical issues, which for a while had my headlights not working, but since I got them on I've been mostly ignoring. My horn won't beep, though, and that's going to be an issue come inspection time in February, so it's time to deal with it.

 

In my adventures around the guts of my car I've found lots of electrical dead-ends and strange fixes to issues that must have come up years ago, so this seemed like the time to trace out my full harness and see what's actually going on. I diagrammed out all the wires between the battery and the firewall, so now I need to get into the cabin and track the dumb wires around under the console.

 

Does anyone have any sage insight on any of this? Particularly if there's a good way to get under there without making pulling the dash apart and reassembling a major project on its own? Should I just give up and run more wires as my whims suggest and leave vestigial cabling everywhere like people have been doing for nearly 40 years?

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I’m afraid that I can’t be much help but I admire your style of writing. I’m in a similar situation with my 78. So far I’ve found that I can get to a lot by pulling the instrument cluster. Between that and crawling under the steering column it’s all there. Pulling the steering wheel will get you to the horn wiring. Good luck!

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It could be that the horn itself is just worn out, try power probing it or testing the wires with a multi meter and having a buddy hold the button down first before taking the steering wheel cover off.

I ruined my horn on my old Camaro back in 96 when the avalanche won the Stanley cup haha!

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Factory service manuals with wiring diagrams online. I even have the good old paper version. Let me know if you want one. I don’t have a working scanner these days.

 

The fuse box itself , and it’s grounding , can often be an issue. Fuses can look good but when removed you’ll find they can be pulled apart as they have separated but when in place look fine.

Just a couple of things to consider while hunting around.

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  • 4 weeks later...

glad to know someone near me has a 70's Subaru.

 

my vehicle also had a few strange things going on,

 

- the 12v positive on the electric fan would switch to negative when it had a load (the fan) but the wires woudn't short or blow any fuse when you would touch the 2 wires together, just capped it and ran new wires like most of the electrical on the vehicle, looked like original wiring too so don't know what was happening there.

 

- same goes for the ignition coil, fuel pump. vehicle has 3 new relays, or should i say the only relays since everything electrical was acting so strange.

 

- when i was driving down the road the headlights would get brighter then dim down every 10 seconds, ran a new ground to the chassis and block and that fixed it.

 

- still haven't fixed the issue with the tachometer though, colder days it likes to read double to triple the RPM's, then read correctly after warming up whatever the tach needs warming up, then after about 45 minutes later i guess what warmed up is overheating now? because the tach then shoots all the way to 6,000 and stays there for the rest of the day, its kind of hilarious. and for some reason the fuel and temp are also connected to whatever is going wrong because those read only when the vehicle feels like it.

 

- Different distributor since the computer thats attached to the coil that reads the magnetic pick up in the distributor was shot and would only work for a few minutes, ended up switching to a points type distributor from a 75 Subaru, works great, just gotta service the points every 5,000-7,000miles.

 

pretty much everything electrical was going wrong with the vehicle unless i ran a completely new circuit, makes you wonder what will happen to all these newer cars 30 years from now.

 

-- Forgot to mention! the tension tabs that hold the fuses are usually pretty weak by now after all these years, try giving them some tension, to all of them. loose fuses will cause some weird stuff to happen, including fuses blowing since theres more resistance present in the circuit, even though theres nothing wrong with that circuit besides the fact that the fuse is barely making contact with all the corrosion and such, something a meter will read as good continuity, but under load is a different story.

best of luck!

Edited by Subasaurus
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  • 2 weeks later...

This is an absolute Hail Mary before I tear everything apart, but my ‘79 BRAT with ‘84 GL engine/drive train has a some viscous electrical gremlins. I replaced the Passenger side indicator can in the front and it all fell apart. The guy who did the engine swap installed fusible links instead of a fuse box, and corrosion in the new running light caused the wires to overheat and the fusible link box started melting. Now I can’t turn the heater fan on for more than two minutes, the passenger side headlights had to be unplugged, and the tail lights or side running lights cause a third fusible link to start melting. Any advice? Clearly I need to get a fuse box, but how can I find the short? I have no automotive electrical experience (shocking I’m sure) but I’ve got a multi meter and beginners luck on my side! Any help would be very welcome...

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I’m sorry to say you’ve got a real mess on your hands. Is this your daily driver or a “fun” car? If you can have it off the road for a bit it would pay to make a deep dive and clean it all up. As electrical systems go it’s a pretty simple one. Study the wiring diagrams and try to find some tutorials on basic automotive wiring, then start replacing everything you can.

 

If it’s a car you’re counting on daily I’d suggest starting from any bulb chase every wire back to its source and check it against the wiring diagram. If you find a bad spot or a shady repair re-wire it with new wire and hack the old circuit out. You’ll get through it all eventually!

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  • 3 weeks later...

Unfortunately, it's somewhere between a fun car and daily.  My dog has a sensitive stomach and intermittent incontinence in the car, so we bought the BRAT as a dog hauler.  I found a fuse box (buried in the parts boxes that came with the car)!  Thanks for the advice.  I think I'm just going to have to continue patching up "the wiring sins of my forefathers" until I get a chance to start ground up.  Summers on it's way so I won't need the heater anyhow...  Still turns over every time, so I got that going for me which is nice.

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  • 1 month later...

I’m sorry to say you’ve got a real mess on your hands. Is this your daily driver or a “fun” car?

 

Mine is my daily driver, but I'm lucky that in central Texas I can get away with riding a motorcycle pretty much year round, so I have a backup plan. I've been plinking at things but it seems like it'll be a long time before I have the opportunity to pull it all. Boy do I want to, though.

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Bonus points: does anyone know where to find a replacement fusebox?

I've been looking on Amazon and all I can find is goofy marina-style ones that use bladed fuses and definitely wouldn't fit in this car.

I asked at my local auto shops (orange, yellow, and green flavors) but they don't carry any kind at all, they say.

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Geez , I just sold one not long ago. Well before the winter anyways. I might have more used , but not likely another new one.

 

Looks like another snow coming - this ain’t Texas - but after that looking like I’ll be able to go through storage.

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Geez , I just sold one not long ago. Well before the winter anyways. I might have more used , but not likely another new one.

 

Looks like another snow coming - this ain’t Texas - but after that looking like I’ll be able to go through storage.

 

I should just send you a wishlist.

That transmission I got from you is going strong.

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  • 2 weeks later...

I probably have a few buried away that I’d need to dig for - like soon but not too soon.

 

Also , I’m still not 100% sure but there’s a chance I’ll just part out my 78 4WD wagon which is the same engine and tranny harness. Again , can’t promise soon. But at least I’m here for backup if you don’t score soon.

 

Most vehicles this old it’s probably not a bad idea to at least trace and replace the wire(s) giving you problems , or create your own harness. Motorcycle folks do it , just a little more for a 70’s Subaru.

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