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Discussion Starter #1
Hello, i posted a while ago mentioning my fog lamps going out after i replaced my front indicators with a clear lense. I never touched wiring or anything, but when i turned on my car, the dash lit up "F/FOG LAMP" and "PARKING LIGHT". Both fog lamp bulbs are burnt out and the front left parking light is out. The next day, my rear left side marker went out and the next day the light in my dash for the mileage is went out. All the bulbs are clearly burned out. Now today, one of my headlight bulbs went out, they have only been in for about 1 week.

Does anybody know what this problem could be? is it common for this to happen on this car? All of the bulbs are the ones that originally came with the car in 1990, except the headlight bulbs.

ANY input or suggestions is greatly appreciated.

Thank you

(1990 e34 525i)

200 Posts
Normal alternator output is 14.25 volts under load and 14.50 maximum.

Get your electrical sytem checked out.

If the regulator is the issue I have a few hints to help.

Alternator Regulator

They can wear into a grooved pattern and the impact of driving can make them vibrate out of the normal groove.

Since the regulator has to increase output to jump the gap it does.

You can clean up the slider rings with abrasive paper.

You can get the brushes as a separate part requiring soldering skills or you can get a Regulator brush assembly for $70.

I would recommend only Bosch, the others are always suspect.

Some instruction for changing:

It is a very touchy installation and about 5% of the installation end in the ground link bent and the alternator not functional.

You can remove correct and reinstall the regulator.

The output must be 14.25 or higher on a Volt Ohm Meter not the dash gauge.

Some hints on the regulator change.

Replacing Alternator Regulator

For those who work on their cars and have not had alternator problems, here is a simple action that should save you down-time and significant costs.

Most alternators on German cars fail due to brushes wearing down (as they are supposed to) between 150k and 200K miles. Brush replacement is very easy -- it should not take over 20 min. and the brushes are attached to a new regulator.

To replace regulator assembly -- back of alternator held in place with two straight slot headed screws. This has a round transistor mounted on the outside on Bosch alternators -- the other type is similar but uses different brushes. Pop the regulator out, after removing the screws.

Fitting the regulator back is simple, but you must install it starting at an angle, to assure that the brushes compress when the regulator is flush with the alternator and the screws are tightened.
You are now ready for 200K miles of alternator life.


1 Posts
KC Ron,
Would you suggest replacing alternator brushes as routine maintenance before failures? And can this be done with the alternator in the car?
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