anyone know how to do this?

[Heysüß]

... find a short.

Fuse 21 keeps blowing out. It's my RPM/MPG/OBC thing. I don't know if this relates to it but my radio and antenna also haven't been working lately.

anyone know how to even begin tackling something like this? I just can't even begin to wonder where to start.

Thanks again r3v!

[jlevie]

Get the wiring diagrams for your car from http://wedophones.com/BMWManualsLead.htm

Trace the circuit from fuse 21 and disconnect items in turn until you find the short.

If the car has aftermarket audio or an alarm, start by ripping that out and restoring the wiring to factory condition as there is an excellent chance that is where the problem is.

[Heysüß]

if fuse 21 is also in connection with the stereo then you're 100% right because there is an aftermarket unit installed and it has its days where there's no power going to it.

[jlevie]

Fuse 21 powers a bunch of stuff, including part of the radio/antenna