Hi I have a JDM Audi a3 (2001) with the single DIN stereo (non-Bose)..
Iv been trying to install a new head unit into the vehicle but am having serious trouble with the wiring.
I have found the ground and the constant 12v, and what I though was the acc. Here lies my first problem. The acc gives me 2v when the car Is off, and 12v when acc is on, however the moment I plug the loom into the new stereo the acc voltage drops back down to 2v. This results in the stereo not starting up. I have fed the 12v constant into the unit to check it and it powers up fine...
Next is the rear speakers and possibly sub?, does anyone know the aftermarket wiring scheme to get these working? Preferably with colours..
Front speakers are working sweet,

So can anyone point me in the right direction. I am good with electronics and wiring, and have installed several dozen stereos, speakers and subs so have some idea what I'm doing, just this has got me stumped..