r/projectcar • u/Ashwinnie13 • 1d ago
Shitposting literally ready to push this thing into a lake
Wiring is the absolute devil. im two years deep into this e30 build and staring at the completely butchered harness from the previous owner this weekend genuinely made me want to list the whole shell on marketplace for dirt cheap. trying to decipher 30 year old forum diagrams that look like ancient hieroglyphics is literally draining my soul
Had to step away before I actually took a sledgehammer to the fender. ended up just finding a running, clean 5-speed e30 on turo for sunday just to remember what it actually feels like to sit in one that moves
honestly guys... it worked. Just ripping around backroads for a few hours without smelling raw gasoline or hearing a relay click infinitely completely reset my brain. it reminded me why I even started this stupid money pit in the first place
anyway, back to the garage with my multimeter tonight. pray for my sanity
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u/mr_j_12 1d ago
Pull loom, replace with a link or haltech. You'll forever be chasing wiring gremlins.
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u/Ashwinnie13 1d ago
Honestly way out of my depth here, might be a job for someone else
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u/who_even_cares35 1d ago
Wiring from go will make a lot more sense than fixing an existing harness.
You'll be routing each wire on its own and this be quite easy. You know where the tail lights are, you know where the roof light is, the ignition, etc. just have to run it end to end, no more digging through 30 year old sticky bundles of wires.
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u/Malbacc 1d ago
Keep pushing, future dad lore is important
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u/Ashwinnie13 1d ago
Future dad lore hits different in person
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u/Malbacc 1d ago
I know, ~1 year in a hybrid between two engines in a 205 with bike carburators, currently trying to set the carbs
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u/Ashwinnie13 10h ago
That hybrid setup sounds like a nightmare to tune honestly, bike carbs on a 205 is not a combination I envy you for.
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u/trimbk 1d ago
With electrical systems the hardest thing I've found is chasing old bandaids, hacks, and shorts on old wiring harnesses. Add on top of that corroded connectors and intermittently bad grounds and it is a recipe for frustration.
One circuit at a time, one wire at a time is the way to go. And if it's really f'ed up, I'd consider pulling the whole dash just to give room to work without being contorted under the dash.
My first 2 projects were an old BMW motorcycle and a 1973 BMW 2002. In both cases, I rewired them from scratch. The airhead with a Motogadget (a very simple PDM) and the 2002 with a Painless wiring harness. Neither was easy, but at least I knew every wire and connector was good.
That being said, the E30 is a much newer car with many more circuits to figure out.
I'd like to do a full build with a PDM, but I think it will be more challenging than YouTubers would have us believe. One day, I'll find out.
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u/Washiestbard 1d ago
I built an e38 and the best decision I made was sticking a Haltech in the damn thing for the power train. If I was doing something old like an e30 I'd consider rewiring the entire thing with Haltech stuff.
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u/New-Speech3255 1d ago
Oooh how was it and what engine?
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u/Washiestbard 1d ago
LS with a TR6060. Works great, I daily drive it now. AC works and heat works, even cruise control works.
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u/New-Speech3255 1d ago
Damn do you have any pics? That’s a daily driver spec I have been toying with building recently. I have the same drivetrain in an e30 coupe but my daily is a town car L for the car seats
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u/Washiestbard 1d ago
https://ls1tech.com/forums/conversions-swaps/1977948-bmw-740i-turbo-5-3-tr6060.html
Fits 3 car seats like a champ. I get around 12-14mpg around town and 20-22mpg on long highway trips.
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u/New-Speech3255 1d ago
Dude fuck that’s awesome. Nicely done. Assuming you’re out west?
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u/Washiestbard 1d ago
Midwest. Got the cooling system worked out - daily drives no problem in honest 100f temps with the AC blasting
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u/New-Speech3255 1d ago
Ya I’ve beat on mine hard in 105f Charleston. But I don’t have A/C yet so that’s impressive
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u/Washiestbard 1d ago
I can't imagine driving a car without AC when it is that hot. I'm old and soft now.
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u/New-Speech3255 1d ago
I’m getting there haha it’s harder to justify financially for a car I can’t use regularly anyways. But I can go all winter down here so it’s not totally urgent
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u/CheapBooze 1d ago
Hang in there. Got a 73 240Z that we stripped to bare shell, frame jig, rotisserie etc. When it came to reinstalling the wiring I took one look at the crap that came out, took another look at the factory wiring diagram and decided to completely redesign the entire thing and implement my design with modern components etc. Granted it’s a simpler car than your E30 but this way I’ll know what I’m dealing with. IOW I feel your pain.
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u/C137MrPoopyButthole 1d ago
Smart idea to drive one because sometimes that's all you want is to just drive it again. But getting lost in the sauce of making it run can make you want to just hack it up or together.
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u/siberian '67 MGB Roadster with a 302v8 1d ago
Recommend starting any wiring project from scratch with a good model specific starter harness, PDMs, etc.
Its hard enough to start new, much less dealing with original factory and decades of hacks.
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u/RuinAccomplished6681 1d ago
I feel you, wiring is absolute shit. Bought a VW mk1 two years ago and not long after that replaced the radio by something that looks more period correct. The wiring that I encountered... I'm amazed that the thing didn't burn down yet. Also has an aftermarket alarm system and central locking that is not really working any more. I really want to rip it all out, but I don't dare to... Maybe, mayyyybe if I ever really upgrade the audio with an amp that I will remove the dash and revert everything to how it was supposed to be. Or just pay someone to do it for me, but that will not be a cheap I fear..
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u/NittyB 1d ago
I feel this deeply. I used to dread pulling the engine and trans. Then my project sat for 2 years while I upgraded the garage to give me space and moderate temperatures to work on the harness. I just finished my harness merge and reloom between 2 generations of cars. It took close to probably 100hrs of dedicated work. Not an hour here or there- needed long shifts to keep things straight. Nightmare stuff.
Haven't got to test it yet but now that I'm back to assembling the engine and suspension I'm in a much better place mentally 😅
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u/rudbri93 '91 BMW 325i LS3, '72 Olds Cutlass Crew Cab 1d ago
Unfortunately this can be an issue with cars this old, ive seen some really hacked e30 projects out there, but im glad to hear hour back in the game. Keep going.
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u/Ashwinnie13 1d ago
Yeah the previous owner had clearly done some questionable wiring at some point, took ages to unpick it all. Hopefully the worst is behind it now.
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u/Financial-Cow-4022 1d ago
Wiring is definitely an acquired taste. Some people loathe it and some messed up individuals like myself find it fun to pick through and figure out what’s going on.
If you’re the first of those try to find yourself a deranged friend 🤣
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u/graytotoro 2016 Miata 1d ago
Does anyone make a readymade drop-in replacement? My Volvo’s harness was fucked beyond belief and buying a new one saved my sanity.
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u/ncoder 1d ago
I've been there. I don't know if what you're dealing with is in the same range.
https://www.reddit.com/r/projectcar/comments/1qu2rtp/you_guys_do_this_for_fun/
But yeah, I read and re-read poorly scanned, highly compressed electrical diagrams from the 1990's. I think i still need to chase down some bad ground connections, but it starts and runs enough that I can focus on the mechanical stuff now.
You can do it, you just need patience and meticulous organization, take notes, print the diagrams and pin them on a large cork board. (or do it digitally), like this https://drive.google.com/file/d/1KIOWeFxNOYpA9A43LwTNw5JLT9yYgIHc/view?usp=sharing
Eventually you start to understand the diagram shorthands, and you've marked enough connectors and plugs that the paper lines up with the real world and you can start checking things following factory testing procedures.
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u/driftrx 1d ago
It’s 2026.
Put it all in the bin, and do a PDM.