Spent an hour or two changing my car bluetooth unit (from 9W3 to 9W7) so that I can stream music/audio from my phone, and also wanted an excuse to fix a wiring issue that was preventing voice control from working from when I installed the old bluetooth unit 2 years ago, not that I ever use voice control - by the time you push the button for VC you might as well have just pressed the button for the function you wanted). Now I can fire up TuneIn Radio on my phone and listen to BBC4 while driving :p
Took some pics to help other VW owners:
Fig 1: Remove 4x T20 screws for RNS510, and 4x T20 screws for climate control.
Fig 2: Pull the climate controls out a tad and the old 9W3 BT unit is revealed, surrounded in foam to prevent vibrations. Rotate and slide out, then disconnect BT.
Fig 3: Some tricky locks on most of those cables to make removing them just that little bit harder (easier if you've done it before). My reverse camera video cable was short, making it even harder for me to get my hand in there. Given that that's the most recent part I installed I'm surprised I didn't give myself more room, unless the cable wasn't long enough. to start with.
Fig 4: Photo of the labels for future reference. Purchased this one nearly 2 years ago now. Now that I actually look at the label I can see the AUX pins (1, 2, and 7). That's where my AUX-IN cable is connected (3 harnesses away though).
Fig 5: Ummmm, which witch is which again? :p One is the original car connector, one is the MDI retrofit harness that I added, and another is for the BT.
Fig 6: Got everything connected and hid the other two harnesses below the bracket that the HU rests on (otherwise you won't be able to push it back far enough). Original car QLC plugs into MDI QLC plugs into BT QLC plugs into the RNS510. I had the MDI and BT harnesses around the other way before since my old 9W3 BT harness didn't have as many wires passing through).
Fig 7: Connect everything back up for testing, don't screw in until you know everything works. I had no audio going to the speakers first time, which had me confused as to what I couldn't connected incorrectly. As I went to unplug a QLC in the chain I heard another click, one of the connectors in that QLC must've popped out, worked fine after that.
Fig 8: Finding my phone. Didn't ask for a PIN which was strange/interesting.
Fig 9: Verify ID3 tags are displayed and track skipping works. Brilliant. 5K0___ is the unit you want, to reconfirm.
Replace screws (be careful when trying to insert the side screws for the climate controls, easy to drop them) and replace trim. Go for a drive if you've been using the accessories/DRLs for ~1 hour to make sure you don't flatten the battery. Even when I turned my light switch to off there were still some lights on (parkers or DRL).