325ix Electronic Probems...

[TAC]

EDIT: Due to a lack of time to troubleshoot I ended up taking the car to the local BMW mechanic and they had it fixed in no time. Apparently it had something to do with some of the front light wires being frayed and contacting each other.

So I recently bought a 1989 325ix off of CL, and for the price I knew there would be some things to work on. The electronics are what've always perplexed me though. Ever since I got the car, the right-rear tail light hasn't worked. I've tried swapping it with known working bulbs and replacing the fuse (#23, which keeps blowing), but finally decided to start opening things up and inspecting the wiring.


The first thing I did was to remove the shift boot and ash tray. There were a couple pennies in the shift boot area, but the real mess is just ahead under the ash tray.

IMG_2404 by TACIdaho, on Flickr

As you can see, there's quite a mess of wires that I, frankly, know nothing about, but certainly don't look factory. It's also worth noting that there's an aftermarket head unit installed.

IMG_2405 by TACIdaho, on Flickr

I have no idea what this little light is for, lol.

IMG_2406 by TACIdaho, on Flickr

I found the the first wrap of two green wires to be contacting each other.

IMG_2424 by TACIdaho, on Flickr

The other, larger bunch, had all the wires separated from contact. (I think the red and black ones might be for the cigarette lighter) Also note the cut off brown wire not connected to anything in the background.

IMG_2422 by TACIdaho, on Flickr

I also found this mysterios couple of wires just in front of the ashtray that I also know nothing about.

IMG_2408 by TACIdaho, on Flickr

It may also be worth noting that the lower steering panel is missing and there's a mess of wires underneath there as well. I know most of these are stock, but there seems to be parts of an aftermarket alarm system as well as a few connectors leading nowhere.

IMG_2409 by TACIdaho, on Flickr

IMG_2413 by TACIdaho, on Flickr

IMG_2412 by TACIdaho, on Flickr

All the wiring by the actual tail lights seem fine, but I can add pictures if wanted. Last thing to mention is that the guage backlights don't work and the heater only blows on the highest setting (seems electrical).

Sorry for the long post, I'm just very inexperienced with the electrical side of E30s and want to make sure I don't mess anything up.

[earthwormjim]

Fuse 23 is for the backlights, so you definitely have a short. Even if you fix it though, the dimmer in the headlight switch knob is probably damaged. It's common for something to short out, and even a slight short fries the dimmer.

The dimmer in the headlights switch is in the return (ground) path for all the gauges, cluster and center console lighting so you can just bypass it, and directly ground everything.

Use the ETM, you need to eliminate one by one, circuits on fuse 23. Take out that headunit too for now, it's probably wired into fuse 23 for backlighting.
I think the SI board does go through fuse 23 for charging it's batteries, if you have the NiCad version, so take out your cluster too. That's probably what fried my dimmer knob and traces in my cluster, an old battery with dendrites forming a short internally. I think the return for fuse 23 goes through the cluster, so don't forget to jumper it if you take the cluster out, to see if there is a short elsewhere.

That bulb I believe is to light up the ash tray.

I have a touring, so I'm unsure if the rear lighting wiring is different, but right rear headlight wiring runs across the trunk from the left side up against the front of the trunk, so check that wire harness for shorts or cut wires.

Electrical wiring can seem really intimidating, but it's honestly quite simple if you take things a step at a time. Get an ETM, a multimeter, and start probing voltages and resistances. When you find something off, start tracing the wires back.

My biggest headache was finding out why one of the fuses for the HVAC system kept blowing, couldn't find anything wrong. Finally dug out the ETM, turns out the O2 sensor heater wire is on the same circuit, looked at my sensor, and the plug had melted.

[TAC]

Fuse 23 is for the backlights, so you definitely have a short. Even if you fix it though, the dimmer in the headlight switch knob is probably damaged. It's common for something to short out, and even a slight short fries the dimmer.

The dimmer in the headlights switch is in the return (ground) path for all the gauges, cluster and center console lighting so you can just bypass it, and directly ground everything.

Use the ETM, you need to eliminate one by one, circuits on fuse 23. Take out that headunit too for now, it's probably wired into fuse 23 for backlighting.
I think the SI board does go through fuse 23 for charging it's batteries, if you have the NiCad version, so take out your cluster too. That's probably what fried my dimmer knob and traces in my cluster, an old battery with dendrites forming a short internally. I think the return for fuse 23 goes through the cluster, so don't forget to jumper it if you take the cluster out, to see if there is a short elsewhere.

That bulb I believe is to light up the ash tray.

I have a touring, so I'm unsure if the rear lighting wiring is different, but right rear headlight wiring runs across the trunk from the left side up against the front of the trunk, so check that wire harness for shorts or cut wires.

Electrical wiring can seem really intimidating, but it's honestly quite simple if you take things a step at a time. Get an ETM, a multimeter, and start probing voltages and resistances. When you find something off, start tracing the wires back.

My biggest headache was finding out why one of the fuses for the HVAC system kept blowing, couldn't find anything wrong. Finally dug out the ETM, turns out the O2 sensor heater wire is on the same circuit, looked at my sensor, and the plug had melted.

Sorry for the super late reply, but I greatly appreciate the help.

Is there a way to tell if the dimmer switch is damaged easily, and does it matter in terms of eliminating the short?

My Si-Board is Lithium, and didn't appear to have any issues, so I' thinking the problem has to do with the aftermarket head unit installed.

Before reading your post I had already started removing the center console and HVAC panel, as well as the gauge cluster to replace the odo.

IMG_2436 by TACIdaho, on Flickr


After taking the cluster out, I found this odd taped up plug going into the HVAC control center

IMG_2440 by TACIdaho, on Flickr


This is the mess that is the head unit wiring...

IMG_2441 by TACIdaho, on Flickr


Another rather suspicious looking electrical bit that I thought I should add

IMG_2443 by TACIdaho, on Flickr


I was wondering what these switches are for and if I ought to replace them while I'm back here.

IMG_2444 by TACIdaho, on Flickr


This plug seems to have no apparent purpose and is cut off on one wire as seen below

IMG_2447 by TACIdaho, on Flickr


Finally, while pulling apart the cluster I noticed one of the backlights was missing. I thought this might not allow the circuit to be complete, but didn't think it would cause a short. Anyway, I could be totally off, but I ordered another just to eliminate as many possible problems as I can.

IMG_2449 by TACIdaho, on Flickr


Hopefully this gives you some signs. I'm pretty terrible at electrical diagnostics beyond the basics so I greatly appreciate the help.

[TAC]

Bump

Still trying to figure out this issue before I start using it as my daily the 29th. The best things I've found in the ETM are on 6300-1, 6314-0, and 6322-0

http://wedophones.com/Manuals/BMW/1989%20BMW%20325ix%20Electrical%20Troubleshooting%20Manual.pdf

Any help would be greatly appreciated, I'm stuck brainstorming and inspecting as much as I can.

[earthwormjim]

You're not going to be able to brain storm your way out of this. You have an unknown electrical system in that car. You're going to have to systematically go through it, match up whats in the ETM, and eliminate what doesn't match.

You know what fuse blows, so that limits the circuits you have to trouble shoot. One by one take each circuit out to find the short.