Audi A3 head unit woas

[maxmc2]

Happy new year all.

Purchased an Audi A3 8P a couple of weeks ago which came with an aftermarket head unit, not Xtrons.

The first thing I noticed was a constant buzzing coming through the speakers.

After some research I realised I needed another harness to eliminate this.

Upon installing the harness I had issues with the head unit and it wouldn't turn on again.

I realised the power wire had come out from the back of the head unit so I soldered this back and re-installed the unit.

All seemed to be fine apart from the unit had constant power now.

I tested the cables and found that I was getting a constant live from the can bus decoder box.

I found another one in the glove box and tried to install that but that one seems dead.

In order to get around this I wired my own switched live and bypassed the the can bus decoders live feed.

I'm getting some feedback when I leave the car which is come from this box because I now have to unplug it when I leave the car, I'm guessing the voltage from this box is causing the issue.

Does anyone have any suggestions what I should do short of buying another unit?

Thanks and sorry for the long post.

[defblade]

I don't really follow exactly what's happening here, but there are elements (HU always on) of a common issue with aftermarket HUs which is that some need the permanent and switched lives one way around, and some need them the other. It's be worth swapping those over between the car and HU's wiring loom and seeing if it fixes the trouble.