OBC, Interior lights and rec counter - resolved

Post Fri Mar 16, 2012 1:52 pm

I have three issues, which i'm kind of lead to believe they are inter related??

The OBC Screen no longer lights up and neither do the interior lights.

These both went at exactly the same time. I had a problem with the drivers side nipple switch not earthing correctly, a quick clean fixed this. But now neither doors or the interior light switch will give me interior lights.

This morning the rev/ econometer counter has stopped working. I think this may be related to the interior lights.
I noticed a week or 2 ago that if i opened the drivers door with the engine running, the rev counter would cut out.

Is there a common earth point is should look for between these three issues?

Just to confuse things even more, a couple of days ago my passenger side headlight stopped working (dipped beam and side lights). Yesterday i pulled the cap of the back off the unit and one wire had come free, the earth i think. I have soldered this back into the cap and now i do get side lights, but still no dipped beam. There is a good chance the bulb has gone and will pick one up on the way home, but is there any wiring in this section that could have caused my rev counter to fail?

Sorry for the wall of text, hope it all makes sense.

Post Fri Mar 16, 2012 3:36 pm

http://www.e30zone.net/e30zonewiki/inde ... g_Diagrams

Have a look at "Ground Distribution". That shows all the earth points and what earths there, so you'll be able to find out if it is a grounding issue or not.

Unfortunately it's not easy to guess where your issue is; you're going to have to be systematic about finding the fault.

For starters though, I'd get the headlight switch off and bridge the necessary pins that should make the interior lights come on. The Wiring Diagrams will tell you which pins that is.

Post Fri Mar 16, 2012 8:07 pm

Thanks Grrrmachine,

Unfortunately i dont speak electrical diagram and have tried to read through them, incuding my haynes manual and cant for the life of me work out what is what.

There is, however, some more news.

I have just realised that the lights under the window switches never go off. Havent had a chance to go through any more than that yet, but somewhere in the system its not registering the doors are closed.

Post Fri Mar 16, 2012 9:54 pm

kolee wrote: I have just realised that the lights under the window switches never go off. Havent had a chance to go through any more than that yet, but somewhere in the system its not registering the doors are closed.

That will be a damaged door pin switch, or a missing plastic button in the door frame that works the switch.
I can't make head or tail of Haynes wiring diagrams either, and the BMW TIS ones aren't much better.
Best diagrams by far are here: http://www.autolib.diakom.ru/CAR/BMW/

Post Fri Mar 16, 2012 10:00 pm

Cheers brian, the site you linked is for 87 onwards cars, is the wiring the same for facelift and preface cars?

Both switches are there and seem to be working, do they earth directly off the door shuts?

I do have another issue too. Going through the haynes manual, alot of the fuses in my box seem to be of higher amp than what the book says. It hasnt caused a problem in the first 5 months of driving, should i bother swapping them for correct amp values?

Post Fri Mar 16, 2012 10:29 pm

325e diagrams are pre facelift, but the wiring is largely the same.
Door pin switches earth by their fixing screw to the A pillar metal.
A fuse that is higher rated than it should be will be fine right up to the time your car bursts into flames! Get them sorted NOW.

Post Fri Mar 16, 2012 10:59 pm

ok,

I'm reading from a very old Haynes, but i think i am right in assuming my E30 is a series 2, in that i should only have one 30 amp fuse and that belongs to the heater.

inside my fuse box i have 4 30amp fuses and they should only be 7.5amp. I have a 15amp in my LH dipped beam slot.

I'm starting to think this could be a reason for so many electrical faults....

Post Fri Mar 16, 2012 11:12 pm

Most E30s have a total of six 30A fuses - 5, 8, 17, 20, 27 and 28.
LH dipped beam should be 7.5A.
There's a coloured diagram of the correct fuse layout on here somewhere, probably in the wiki.

Post Sat Mar 17, 2012 7:51 am

http://www.e30zone.net/e30zonewiki/index.php/Fuse_Box

Post Sat Mar 17, 2012 11:36 am

OK, i pretty much figured out the problem...

Its me and my complete lack of competence in this area.

The solution: a customer i do mobile phone contracts for is an auto electrician, he is coming out to see me next week.

I will let you know what was/ is causing these problems then.

Also, the fuse layout in the haynes manual is slightly different to the one linked above. Is the a reason for this?

Post Sat Mar 17, 2012 12:30 pm

The only key difference I can see is that the reverse light has moved from fuse 9 to fuse 10. All the other differences are simply additions to what you already have, such as the introduction of the OBC wiring on various fuses, and the Touring rear wash/wipe circuit on fuse 26.

Post Thu Mar 22, 2012 10:51 am

Auto electrician came out today. Problems fixed.

Turns out at some point the headlight connector had shorted out and melted the earth connection, bot on the wiring connector and the cap that screws onto the back of the headlamp.

Didint have a spare connector or cap, so simply did away with both and connected directly to the bulbs.

Oddly enough, this was causing the fault with the internal lights, the electric arial and the rev counter.

All are back to working again

P.s. Only charged £40.00.