Have a question about wiring for an aftermarket stereo. I've done a bunch of research, and found what seemed like some good DIY instructions, but some of them don't match up to what I have. My car is a 1988 325i Convertible with what I've been told is premium sound.

I've removed the factory radio and unplugged the in-dash fader, and then unwrapped the wiring from the fader back to a splice, or "Y" section of the harness. I've followed the remaining wiring by hand back up behind the gauge cluster and have found that the wiring does not pull out any further, and there is no other splice, plug or other point where wires seem to be spiced together.

So far, based on the instructions I found and looking at the wiring after the point where the radio and fader wiring joins together, I've identified that the RED/GRN wire is constant power, the Violet/Gray wire is switched power from the ignition, the thickest of the three BRN/BLK wires is Ground; I've also identified that the YEL/RED wire is LF speaker POS, the BLU/RED wire is RF speaker POS, the YEL/BLK wire is LR speaker POS, and the BLU/BLK wire is RR speaker POS.

There are three additional wires going back into the dash from the "splice" point. Two are white. My assumption is that the single wire (see pic) coming from the radio opening is to the remote antenna, the other white wire that goes into the wire harness is to the amp. There is one remaining BRN/BLK wire in the wiring harness.

Do the speaker wires have a ground wire associated with them? If so, which wires are they? Is my assumption about the white wires correct, or is it just the opposite? What does that last BRN/BLK wire go to? It may be a ground wire, but then it's the only one in the whole harness.Name: Stereo wiring.jpg Views: 35840 Size: 92.3 KB