electrical problems

[dennoz]

Hi, well this is about my headaches with this car. For the past 1 week, the struggle has been real and the issues I face actually make me get more tired of the car daily.

Prior to starting my build, M52B28 swap into my 92 E34 520i, I acquired another clean, perfect E34, a 91 E34 520i running an M50B20 engine.

92 E34 - BC09429
91 E34 - BC05400

I decided to put the M52 in the 91 car and swap the M50 from the 91 to the 92 E34. Before the swap, everything in the car was working well, everything in the interior, the lighting the cluster etc....everything was okay.

Mechanically everything was okay, the M52 just needs an M50TU harness to complete the OBD 1 swap and the M50 swap in the 92 went sucessfully. So after the initial start, issues started popping up one by one.

I swapped the code plugs from each instrument cluster, all were the gen 3 clusters, same cluster, same SI board, etc....and then issues started. This is regarding the 92 E34; All my interior lights completely went off, the instrument cluster was working well then all of a sudden nothing worked. Only the temperature gauge, speedo and LCD screen work plus the initial signs, battery, oil pressure, brake pads, etc when starting. The tacho, fuel gauge, fuel consumption literally stopped working and also the blower only works in stage 4.

Another wierd thing that started happening is that the indicators, whenever I put the hazards on, they work pretty well for close to 5min before freezing and only the right side indicator stays on without blinking, kind of stuck if that's the correct word.

Then my wiper system began chewing, and I literally mean chewing the fuses in the rear fusebox. It's designated to run a 30A fuse but whenever I engage the wipers, the fuses are melted upon the 2nd click and that freaks me out. Tested it with a 40A fuse and worked well until it rained yesterday and the wipers stopped functioning, which most likely might have melted that as well.

I've replaced each and every fuse in the car more than 5 times, bought over a 100 fuses to replace in both fusebox but still nothing is working. I'm not an electrical guy but I'm pretty sure something is messed up in the car. Before I forget, when I swapped the M50 engine, I swapped the engine harness as well, so might that be an issue or something of the sort?

Kindly help a fed up owner.

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[moroza]

Tested it with a 40A fuse

Because you say you're an electrics newbie, I'll patiently explain why this is a big no-no: fuses are designed to be the weak point in a circuit, to blow cleanly if the circuit gets overloaded (which means running more current than intended). They are FAR easier to replace than wiring, and unlike wiring, rarely cause collateral damage when they blow. If you upsize a fuse, you now make the wiring the weak point, and if the circuit gets overloaded for whatever reason, the fuse may survive but the wiring overheats, melts, and because wiring is usually in big bundles, it melts other wiring and now you have one bad mess on your hands.

You have unrelated systems all acting up. This usually means one of two things:

1. One bad circuit overheated and damaged other circuits that are logically unrelated, but physically wired very close to each other. This happened to me, and the way I untangled that knot was to pick a random loose string and follow it until I found results. In my case, it was headlights that wouldn't turn off, so I started tracing continuity and power from the light switch into the fusebox, where I found a large bundle of melted splices.

2. It could mean is a central problem with the alternator.

Either scenario needs a multimeter, preferably digital. The second scenario requires just a voltage test on the alt. The first scenario may become a big job, but while I can walk you through all the steps... you're honestly better off, at least in Scenario 1, finding help from someone local who's good with electrical circuits (a household electrician is at least as good as a car mechanic).

You'll want these: http://www.armchair.mb.ca/%7Edave/BMW/e34/ They are for US cars, but most of the wiring is the same.