Wiring Audi A3 without VW1 "T-Harness"

Group using the VW1 firmware for Media Device Interface (MDI), Multi-Funtion Display (MFD), bluetooth, amplifier turn on, amplifier digital fader, amplifier gain adjustment, steering wheel control, custom gauges, vehicle info, park assist, Navigation arrows on MFD, climate status screen...
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XTRProBoy
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Wiring Audi A3 without VW1 "T-Harness"

Post by XTRProBoy » Mon Jun 25, 2018 6:53 pm

Hi,

I noticed recently idatalink released Audi A3-compatible f/w for the RR, something I was always looking forward to given they've had VW firmwares for similar PQ35 cars--thank you! :) (For reference I have a 2013 Audi A3 quattro.)

Given this, and feeling the need for a newer/faster unit, I upgraded my older Kenwood DNX model to a newer Maestro-compatible DNX893S.

Previously I've had PAC interfaces doing the CAN and SWC interfacing and that's how the 893S is working right now but obviously I bought an RR for the additional data features and am going to install it in the near future.

I just had a few questions about wiring it up. I didn't buy a VW1 because I'm not sure that it's necessary given I already have a standard aftermarket-radio harness that plugs into the factory quadlock. I noticed in the f/w manual it shows connecting an OBD plug to the OBD port on the vehicle, however on all pictures of the VW1 I've seen there actually isn't an OBD plug on it! Also this doesn't come with the RR (and I've seen it in pictures of other idatalink T-harnesses but not with the VW1) so I'm assuming then the interface wires up to the Can H & L wires I already have connected to the existing interfaces?

I noticed a comment on another thread though where someone was trying to get an older A4 (which has different electronics):
"If your plug is different than the VW1, this solution will not work for you. Hardwiring will not work because the codes on the car's data lines are different when the plug doesn't match."

I don't understand what this means though? Where does the VW1 tap into the CAN and/or OBD connections in the vehicle? As I mentioned I don't think there actually is an OBD plug with this harness as the f/w manual depicts. If it uses the Can H&L (and only those) from the quadlock, shouldn't the RR work fine if I wire up to those wires from my harness?

Also another couple questions I have regarding future development of the f/w. It looks like this is "low-demand" f/w but I'm wondering about the possibility of the following things:
1. I noticed when I flashed my interface today, there's oddly no support for the OEM "Mode" button on the steering wheel (the left hand rectangular button). I find that a bit odd given much older and less sophisticated SWC interfaces have always supported that button. There's only two main buttons (plus the "click" features of the two scrollers) so I wonder why there's no support for one of these buttons? Is it possible idatalink will add this in the future?

2. I think this one is a lot less likely but the OEM nav in the car is able to send turn directions to the MFD/DIS screen in the cluster. I believe this is supported by RR on VW models but I don't think it is on Audi, though it seems the MFD is supported insofar as radio/music metadata and phone calls... Is there any chance of adding the nav directions on Audi displays as well or is this unlikely to happen?

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Dara DeGrand
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Re: Wiring Audi A3 without VW1 "T-Harness"

Post by Dara DeGrand » Tue Jun 26, 2018 8:57 am

Long story short: The VW1 harness is listed as required, which means you need it for the install. We tie into multiple can systems with that harness. The newer versions of the harness do come with an OBD2 connector for you to plug in in lieu of hardwiring it.

1. The mode button goes to the cluster, which is why we don't support it.

2. Nav in the MFD isn't supported; Metadata will likely come through. Occasionally, we have seen cars where the messages the cluster needs to see are different so it doesn't show on the radio, but more than likely, you'll get song/radio information.
Dara DeGrand
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XTRProBoy
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Re: Wiring Audi A3 without VW1 "T-Harness"

Post by XTRProBoy » Tue Jun 26, 2018 12:15 pm

Thanks for the assistance.

I kind of now see, after taking the cables out of the box, why the harness is "required". It seems the RR has more harness connectors on it than it has wiring harness provided with it. The black and green 10-pin connectors, most notably, don't come with supplied harnesses. It seems you can only plug into these two with the T-harness which has plugs that fit. Of course one might find harnesses to plug in here it's probably less effort to just buy the idatalink harness. I do find that a bit silly TBH, and it seems like a waste of my existing harness which probably has all the same wired connections, but it's not a huge deal to get the "required" harness.

I do think the RR is a fantastic product for what it is and what it costs, esp. on vehicles where it has a lot more features than on mine. Just seems kind of odd it wouldn't come with those two harnesses but then I guess I'm fairly old skool and was used to doing things in the 90s where you'd sometimes have to wire your own relay blocks, use diodes, etc. to do door locks and to get certain features working for things like alarms and starters. I get that these days there's a lot more "plug & play" elements to adding aftermarket electronics though.

Anyway that said I'll try to see where I can get the harness or just order it online somewhere. Will let everyone know how it all works out once I get it installed :)

I still don't get why the Mode button can't be operated given all the other things an RR can do, in general. Mode works fine with other SWC adapters. It may "go to the cluster" but there's certainly still a CAN message on the bus when the button is pressed, so it should still be usable. I know that what happens with other adapters is, if you have the factory BT, pressing Mode will activate that on/off in the display while also operating the stereo but this can be avoided by disabling the factory BT in the CAN installation gateway (using VCDS or similar) so the car thinks it doesn't have BT--either that or just unplugging the factory BT module. Once that's done the button seems to do nothing for the car/cluster and works solely with the SWC adapter. TBH though it works, I don't really use it that often as it cycles through sources and it's easier to just select the one you want on the head unit. But it would be nice to use the button to do something else altogether like activate the gauges display.

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