When you turn on the ignition and all of the electrical BEFORE the car STARTS, I get this buzz and vibration coming from inside the dash near the AC and radio, basically high center. I know there is always a buzz AFTER the car is SHUT OFF on most e34s in the same area, but this buzz is louder, it rattles, and it doesnt stop after 20 seconds or however long the other one lasts. This continues until you turn the electrical off.
Also, my air conditioning fan seems to cut on and off randomly in long intervals if I turn it on, so I don't know if this is connected or not, but it's all in the same area so it could quite well be.
Quite convinced you have a blower issue with the A/C. Try removing the fuse F19 (Blower fuse). If the ratling stops, yes it is the blower.
how much new water pumps cost that would also help me a lot, because apperently mine is not circulating enough and I'm running hot.
I paid about 50 USD for a 535i one last time, but you may need a new tstat or fan clutch instead of a new pump. Check Bruno's site on Overheating.
http://www.bmwe34.net/e34main/trouble/overheating.htm
my *brake light* warning comes on. (I heard about an "LKM" problem and there is something in the fuse box, please explain if this is the problem)
Understand Break light is different than break light circuit. If lights are OK, check your lamps sockets, use original lamps replacement only, and yes, check the LKM, also per Bruno's site.
http://www.bmwe34.net/e34main/mainte...trical/LKM.htm
I get a warning saying +38 degrees, or +18 degrees (whatever the temperature it says)
If it is what I guess (OBC warning), it's -38 (or about, not sure on the exact value) degrees, it is typical from a disconnected thermo probe in the front bumper, telling the OBC that temperature is extremely low.
The OBC displays an alarm when outside temperature is below -3 degrees (or about, not sure on the exact value) in order to warn you that there may be ice surfaces on the road.
Good luck
Javier