How To – Bluetooth Audio

How To – Audi S4 (B7) adding Bluetooth to RNS-E audio, needs access to VCDS 

Thought I’d share my solution for adding a decent digital audio (MP3) solution to the standard RNS-E audio system in the B7 S4. The existing SD card has huge limitations on card size and the fact that all modern SC cards will not work. I had to buy old 2GB cards off eBay, these are becoming increasingly difficult to find.

My car had an existing iPod connection for a classic iPod / old iPhone which worked via CD disk 5 this worked but other than play from the head unit there was no display of music detail (album, artist, track etc).

I therefore purchased an Xcarlink unit with a Bluetooth adapter which had a modern SD card slot which would take large capacity modern format cards. When installed however the Head unit still did not pick up music from the new SD card and there remained the issue of failure to read or control the music via CD 5 (which I assume is the default way the unit picks up external units such as the Xcarlink). In the end I gave up on the SD card / connecting my old iPod and just played from my phone via the Bluetooth unit.

I recently purchased an Xcarlink universal wireless Bluetooth V4 to aux receiver for a project for my Elise. This has a neat control pad from which you can increase the volume, skip back and forward, pause, play. The whole solution is around £30;

  • Xcarlink unit rrp around £38 however I found a seller on eBay with Make An Offer who accepted £25
  • 3 x 0.5mm female connector
  • electrical tape, 3 lengths of wire around 15cm, electrical connectors and some heat stink sheathing.

The basic idea is to take the Xcarlink unit, remove the RCA connectors and strip back the outer insulation, this will expose the red and white wire, removed the wire protection. Now attached one of the new wires to each of the two red wires and the third to both of the white earths.

Now connect the new micro connectors to the three wires, then use either insulation tape or shrink sheathing to cover the connectors almost to the tip (this is important).

If you can find one an alternative to this step is to find a 32-pin A/V input connector (part no.: 1J0 972 977 G) either with wiring connected or a used one you can butcher to connect to the appropriate pins.

Now using VCDS you are going to activate Aux input on the RNS-E, this will allow you to select CD/TV and activate Aux input via the Source button.

  • Connect with module 37 – Navigation
  • Choose procedure 07 – Coding.
  • Read original coding (e.g. 0205115). Write down this number.
  • Change second to last digit by adding +4 to current value. E.g. 0205155.
  • Enter and save new coding.
  • Exit.

Then you need to connect the three wires to the following pins on the 32 pin connector at the back of the unit, the insulation almost to the tip of the connector is to prevent shorting when you push on the three connectors;

  • 22 – left channel
  • 6 – right channel
  • 21 – ground for both channels

Then connect to a power supply from on the unit and Earth to the unit via the small screw at the back. Test it all works before fitting the unit back in place plus run the control pad out through the side of the dash (remove the panel under the steering wheel). I fitted the control pad using the adhesive pad that came with it to the left of the steering wheel – You are good to go!!