Humming sound from dash with key removed

[tritone88]

Hi I just bought a 93 325I with 135K miles that has a few problems. This morning I started it and then decided to drive my other car. WHen I switched off the ignition and removed the key, I could still hear a motor/fan sound (a humming) coming from the dash below the radio. I've never owned a BMW before so am new to how these cars behave. I do all my own mechanical work and would love to learn about these cars. If anyone knows what this might be please let me know. Thanks.

P.S. Some other issues while I'm at it. 1)

The radio only has static unless you wrap it firmly on the side, then it comes on .

The sunroof only opens and closes. It doesn't do the tilt up thing anymore. Might that be just a switch?

Where does one check the transmission fluid in these cars? The owners manual makes no reference to it. As part of the maintenance routine, should I flush it and refill with SYnthetic?

Last but not least. I need a catalytic converter to pass emissions test. Are the aftermarket Kraco's okay?

[kassper]

As for the humming my friend has a 91 528 and his does the same. I'm sure its normal, but could be wrong. Never thought to ask him what it was but he doesnt seem to be bother by it.

[jrhaile]

my 95 325i does the same...

[Relevart]

Humming,
I think you can here ABS pump coasting to stop. You can't here it while motor is running because of other noises. But I can be wrong...
Radio:
Sounds like antenna cable has bad contact in the socket of the radio. I do not know, where it is in your car.
Sunroof,
Can't help you there... don't know...
Transmittion fluid:
If you have AT, I assume so, then there is now access to it from under the hood.
You have to raise car. There is a plug in the transmittion case it is on driver side of transmittion, closer to the top and, if I remember correctly, close to the center of the case, slightly to the end. It is easy to find it and take it off, but it isn't so trivial to fill it. You'll see it... How to check ATF? I guess, BMW doesn't want to judge condition of ATF: just change it at specific intervals. About level: you have to fill case, untill it doesn't take it any more. On my other old car, I would stick my little finger in the hole, if I feel oil right below edge of the hole, then it is OK, if not, then do something.
Can't help you with Catalytic converter.

[onsinkingground]

Totally normal sound.

Replace your radio with an aftermarket unit, they go bad in way too many cases anyway.

There is a process in which you soak the switch in rubbing alcohol and then wash it, dry it, and replace it which apparently cleans it out and makes it functional again. Give it a try.

[tritone88]

Thanks for all the responses from everyone so far. I did find an archive about accessing the transmission fluid. I'll try cleaning the sunroof switch. Several people responded writing that their cars also had the humming sound, but no one has said what it is for sure. Don't know enough about where things are on the car yet so I can say whether or not sound is coming from ABS pump. It really sounds like it is in the dash not inside the engine compartment but sounds can be deceiving.