Reverse lights, Interior lights, Tach + mpg + 13 button obc + Radio.

[Ebon]

Well, at least my headlights still work!

I have a host of electrical issues with my 1987 325is.

My tach, mpg, and obc work sporatically.
When I first bough the car, they didnt work at all, but since its gotten warmer they now work at random.
I downloaded the electrical troubleshooting manual, and checked the ground under the kickpanel but its one of the cleanest pieces of metal on the car.

I swapped out every fuse in the car.
The radio (aftermarket.....) Doesn't get switched power, thou when I bridged the constant and switched power to get a cd out, turning th key off turns off the radio..

Also my reverse lights work completely randomly, independent of the obc and tach issues...

And on top of everything else, My interior lights refuse to work. never have.
I'll restate thou, all fuses (sp?) are good and I checked the grounds.

Any help??

[zig553]

I know you said you checked your grounds but did you check your battery ground? Because on my E30 my battery ground cable was corroded and old. When I replaced it, a ton of electrical problems went away and made my alternator whine a lot quieter (its still there a little) Also it made my radio stop turning off and on at its own free will. That or maybe damaged wires in a harness somewhere? Maybe even try a new battery or alternator?

[Ebon]

I know you said you checked your grounds but did you check your battery ground? Because on my E30 my battery ground cable was corroded and old. When I replaced it, a ton of electrical problems went away and made my alternator whine a lot quieter (its still there a little) Also it made my radio stop turning off and on at its own free will. That or maybe damaged wires in a harness somewhere? Maybe even try a new battery or alternator?

When I first bought the car, I scrubbed the battery terminals and the wires with a steel brush. I didnt scrub the main ground down thou.... I may try that tonight, thou now my tach an obc come one, but the obc forgets all of the settings whenever is turn the car off.

[Ebon]

Bump for backup?

[bernzpeed]

check if the bulbs are loose in the tail lights/ back up lights.

[M-technik-3]

Check fuse 11? Check it. Yes you said it's good but the reverse switch wire goes throuht the boot and tends to pop this fuse which effects all mentioned items.

[Ebon]

Check fuse 11? Check it. Yes you said it's good but the reverse switch wire goes throuht the boot and tends to pop this fuse which effects all mentioned items.

Mysteriously enough, I did notice something a little funny going on with the seat for fuse 11. I was going to pursue it further, but everything works intermittently now. even after I cleaned the reverse bulbs..
Im going to open up the fuse box to make sure, it could be the wiring in there

[M-technik-3]

Check the wire thru the boot it tends to fray

[khalild]

pull the drivers seat and check the splices along the drivers side under the carpet. I bet a few of them are corroded.

[Ebon]

From the dead.


Alright, after almost eleven months I can bring the following information:

With the bridging of the constant and switched power on the radio, the radio will still come on with the key, but won't remember any settings. I also dont know why bridging the two will turn it on with switched power, instead of it always being on. Kind of stumped there.

Obc has been swapped but new one still just lights up. No data, just a lit blank display. I swapped the instrument cluster to one that has a fully working tach and mpg, but also has flickering service lights.... so it could still be si related.
New cluster should be getting shipped today.

pull the drivers seat and check the splices along the drivers side under the carpet. I bet a few of them are corroded.

I never got around to pulling the carpet...... probably should. I just read the guide and will try it the next time the weather around here dries a little.

The overhead, glovebox, and trunk lights still dont work. I was able to find and clean the ground by the break pedal, but it did not resolve anything.


I also noticed there was/is some charring on a couple of the seats in the fuse box. Ill snap a pic at some point today, but was wondering if you guys know of a write-up to swap the top or the whole thing. Hoping that may possibly resolve something..


If you need any pictures of ANYTHING just let me know, Im ready to start making progress!

p.s.: I'm currently strung out on coffee and frustration after spending a majority of the night reading the etm and bentley trying to figure this as well as an mpg issue out. Sorry If I'm at all incoherent. :yawn: