Anyone know have a wiring diagram for the amp in the back?

I'd like to rewire it to stick my own input in there, rather than the radio.

I just did this. Let me assemble the info/pictures and I'll post later tonite.

hey thanks :)

what did you plug in? a headunit?

These are the plugs at the amp in the trunk. You can trace the colors from here to the radio audio outs if you need to find them up front. I put a new amp in with the OEM head unit. When I change the head, I'll run patchcords back from it to the amp and won't use the oem unshielded wires for input. saavy? Another note- notice the door and kick panel spkr share the same ground, so do the 3 spkrs in the rear enclosures(wuff/mid/tweet). If you are going to bi-amp or more, you will have to run independant grounds to all spkrs.
http://bmw.satservice.com/stereoplugs.jpg

Great post, Some share the same ground on the speakers? I had to do it the hard way to install 2 sets of component speakers, Thanks!

I took the two plugs out of a blown OEM amp and built an adapter to plug into my aftermarket amp. I am using the OEM head for now, so all I have done is installed a newer/more power amp in the same cradle the OEM was.
I didn't want to cut that harness, this way all can be returned to OEM unblemished. And here's what that looks like-
http://bmw.satservice.com/stereoadapter.jpg

nice one man.

I'm doing something slightly different. Which is to remove the headunit and replace with a PC, so I need the input to the amp. it's the white wire (+12v HU on) that I was worried about most as in the E39, the amp would only go on using a pulsed ibus (10s frequancy). So the PC had to output this every 10 seconds using the ibus adaptor or the amp would go off!

Regarding the OEM wires, I think they're in a twisted pair arrangement. They were on the E39 anyway. This means although they're not sheilded, they're less likely to get interference, and they're probably wired up so that they don't run parallel to any power/rf emitting wires. I would suggest to use the OEM wires first and see if noise is an issue, before running new ones and risking getting noise. Unless you plan on really checking where all the wire looms are etc!

Thanks for the pics, I'm sure I'll be posting here again!

OEM harness is not twisted pair. You can find amp inputs by color at the radio from the previous picture. I just labeled them as radio outputs instead of who was FL,FR,RL,RR. Really didn't pay attention while soldering, I just plugged the rca's I soldered to the adapter after I powered everything up and faded/balanced the radio to id them. My amp gains are full down and there is still quite a bit of white noise from the radio. It's not the wiring, it's the radio. If/when I swap head units, I will run shielded patchcords for the amp inputs. The white +12 is working fine with my amp, no ibus.

fabuolus :) just what I wanted to hear. thanks man