On my 1991 245SE, I get battery light, brake faiklure and ebrake warning lights flickering after the car is warm. I checked the Alt wiring and it seemed fine and I cleaned all connections.

Being that it starts after running about 10 minutes and it is somewhat rev dependent (not exclusively though), I'm thinking voltage regulator?

I have 2 extra alternators that I can swap but wanted opinions prior and hoping it isn't my harness.

TIA

Another possibility is the wire bundle that passes under the crank. Oil drips on the insulation exposing bare wire. It's easy to eliminate it. Move it around and then start it up.
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1980 240 335k 21 years.

I am leaning toward bad Brushes too.

Ever do them before?
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Fiickering dash lights is the classic symptom of worn brushes in the alternator.

First time this happened on my '91, I soldered new brushes in to the voltage regulator. The second time, I spent a few bucks and bought a new voltage regulator, with brushes attached.

Easy to replace, just two screws hold it in. Easier to access the screws when the oil filter is removed.

Guys, I just had this problem within the past couple of weeks. I urge you to fix this fast. My car died on the side of the road on my way home from work. Ended up being the brushes were severely worn and the alternator was not charging. My car was running off of the battery and eventually died. I ordered a new voltage regulator from FCP Groton and that fixed the problem. I'm happy I did that versus messing with installing new brushes. Good luck. I ended up removing the alternator and installing the new voltage regulator on my workbench.