Nexus 7 Head Unit Installation – Part 10 – Amplifier Turn On

Nexus 7 Head Unit Installation – Part 10 – Amplifier Turn On

Where We Left Off: Amplifier + JoyCon

If you’ve been following along then you may already know that I’ve gotten super close to getting this all working. I’ve had to go back to work after my Christmas holidays and a lot of time is basically spent waiting for things to arrive. Essentially, I have two problems left to solve:

  • Noise created by powering up the tablet with a JoyCon connected
  • Factory Bose amplifier not turning on with my setup

And that’s it! I could drop my headunit in, but I’d be rockin’ the speaker on the tablet, and that might be kinda lame. So, I’m holding out.

Bose Amplifier

So I did make some progress on this! I got in contact with Christian again at Enfig, and he linked me to this forum post. Turns out my car is coded to have the amp turn on over CAN bus. So, my options?

  • Find someone with a VAGCOM to do the programming to switch for me
  • Buy a VAGCOM to do it myself
  • … Buy a new harness.

The first option would be awesome, except I tried and I don’t know anyone with a VAGCOM. I could probably go find a local shop to do the programming for me, but I’m looking at spending probably an hour or more worth of labour for something that’s pretty trivial if you have the hardware.

The second option would be kind of cool, especially if I have cars in the future that can take advantage of this. Problem? The Canadian dollar is abysmal. The $300+ US price tag also hurts a bit.

The third option seems pretty bad considering how far I got with this harness. A new harness has around a $100+ US price tag on it, and the shipping time… But both the other options have a crappy time component to them as well.

The New Harness

Spoiler alert: I got the new harness. Here’s why:

  • Christian at Enfig was really helpful and said because of a miscommunication, he’d be willing to refund the other harness if I sent it back
  • I still might be facing the dreaded “low volume” problem that’s common for stereo swaps in Audi’s with Bose systems…

And the best part? The harness came in like two days. Awesome!

Unpacking the harness made me realize a couple of potential challenges:

  • This new harness didn’t have any RCAs… The old harness I had my audio hooked up over RCA jacks
  • This new harness used a different box for steering wheel controls… So I’d have to reprogram my JoyCon or figure out what the heck to do with the box.

My first trial with the new harness and my phone didn’t go so well. I wired up an 1/8th inch jack to the back-left speaker connections on the harness and attached the harness to my car. I turned the key, pressed play on my phone… and silence. After pondering for a bit, I figured that the steering wheel control box that came with the new harness probably works some other magic. The second attempt was with the box on the harness. Again, key in, pressed play… and no music. Somewhat baffled, I said to myself “the only other thing here is this other ‘AMP ON’ line that the old harness had”… So trial three was the exact same thing but with the AMP ON line attached to switched 12V.

Bingo.

Looks like the PAC steering wheel control box that came with the Enfig HiLo harness does *something* to make the blue AMP ON wire actually function. Cool beans.

Steering Wheel Controls

So now my harness has functioning audio. This is the only thing my last setup DIDN’t have. Because I need the new PAC steering wheel control box attached to the harness to get audio, this means I had to find a way to make steering wheel controls work with the PAC box!

I tried hooking up my JoyCon to the PAC box and playing around with the settings, but I couldn’t get any meaningful readings. After about 20 minutes of fiddling, I realized that I was being a total idiot… The PAC box is spitting out digital signals for the steering wheel controls, and my JoyCon is still expecting analog signals. Duh.

So I hit a bit of a wall. I can have audio with my new harness, but none of my steering wheel control setup from before would work with the PAC box… And I need the PAC box to actually get audio! So, I took a leap of faith.

I spent the better part of this weekend trying to figure out what each wire on the harness was actually doing, and then splicing into the new harness to get the cables I’d need to hook back into my previous Enfig steering wheel control box. If this would work, then it would mean I have the PAC box for my amp turn on (and it would have some digital steering wheel control output that I wouldn’t use) AND I’d have my Enfig steering wheel control box attached to my JoyCon. After much trial and error (including having all of the wires on the Enfig box put in backwards at one point), I managed to get the new harness working in conjunction with the old steering wheel control box.

I’ll make sure to get a big ol’ wiring diagram up for all of you once I finalize the connections, and I’ll try to edit this and put a link back here. I couldn’t use the connector from the old harness (since I’m returning it) so I’ll likely solder right onto the old Enfig box if I can’t find any suitable connector alternative.

Next Steps

At this point I have:

  • A new harness setup that seems to work for everything I’ve tried!
  • Working audio
    • Amp turn on
    • All speakers get audio
    • 1/8th inch male AND female input on the harness
  • Working JoyCon USB mapping
    • Vehicle speed sense
    • Reverse line
    • Steering wheel controls (minus the “mode” button, like before)
  • Functioning tablet
    • Powers up and down properly
    • Has the initial software setup I wanted to try out (Timur ROM + Google Now + Google Maps + PowerAmp + TabletTalk)
    • Terabyte HDD
  • Extra inverter
  • Extra USB cables

So next steps include:

  • Finalize connections to Enfig steering wheel control box (Solder or other connector alternatives)
  • Wait for my time-delay-relay to try out fixing distortion problems with JoyCon
  • Route constant 12V from fuse box to behind dash
  • Route inverter cable from glove box to behind dash
  • Route USB cables to convenient parts of the car

7 thoughts on “Nexus 7 Head Unit Installation – Part 10 – Amplifier Turn On

  1. Nice work on your TT, I’ve heard minimal about android for auto, now I wish I checked out your site earlier. I’m fascinated with how far the android community has come with supporting otg, fast charge etc. I thought my HUD app using the gps to calculate speed was cool enough. Looking forward for some action shots!

    Keep up the great work.

  2. Hey,

    Nice work and thanks for sharing all the info on your blog,
    there isn’t much other info out there,
    and the android radios I have seen don’t look great (screen size, weird roms etc)

    Cheers

  3. Very nice car bud.

    Did you ever finalize your Joycon setup? I’m running a Nexus 7 setup in my ’07 RS4 except I’ve completely ditched the factory junk and installed a compact amplifier in the glove box with front door components.

    I was running a half depth head unit in the glove box to get steering wheel volume control, but I realized running the signal direct from the DAC to the amplifier provides a much better signal. Now I’ve got my Joycon EXR in hand and the Enfig SWCL-UNI en route. I tried cutting the Pioneer steering wheel control adapter but couldn’t get any signals.

    Anyway, it would be cool to see some updates on your stereo setup. I’ll update you once I’m finished with mine. Hopefully I don’t run into the noise issue you were having with the Joycon.

    1. Thanks for the kind words!

      I had steering wheel controls working at one point, but that was only when I Frankensteined two Enfig harnesses together. When Christian made me a custom one, the way I was trying to use it caused distortion when I had the joycon plugged in. No fault of his, but just too many variables for me to go back and forth with him on.

      Unfortunately, I’m not going ahead with this setup anymore. I cracked my bezel and I haven’t had steering wheel controls for months… So I bit the bullet and I’m going to a professional installer for a complete audio overhaul. I’ll be getting an android auto compatible head unit.

      I’ll get some pictures up once it’s all installed, but this is the headache free way for me lol keep me posted for how your install goes!

      1. Man I spoke too soon. I went back to the car and plugged the Enfig harnesses in the correct order… and it all works!!! It sounds amazing after bypassing the head unit and I have full audio/track control! No noise/distortion either… I’m really stoked I got this working.

        This weekend I’m doing sound deadening, fast rings, better speaker mounts, and new door clips in the front doors. Last step is getting a good looking and easily detachable bezel to finish it up. Any tips on the front? I think I’m just going to put some light adhesive strips on the back of the Enfig bezel I cut up.

        Sorry to hear you’re giving up on it. I’ve been tempted to hire a professional installer multiple times during the process of getting this Nexus 7 install right. I’ve seriously gone through several major revisions of this setup, but I’ve got it perfect now and I can leave it the heck alone.

        Thanks again for your tips on wiring the Joycon to the Enfig steering wheel control harness, they were spot on.

        1. Awesome! Glad to hear it worked out!

          If you want adhesive to help keep it fixed in place, check out some 3M tape from Amazon or something. Good double sided tape. If you’re looking for ideas to make it removable, I played around with some industrial velcro… It works, but it won’t sit *perfectly* 🙁 the Enfig bezel is the best looking one around though!

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