I'm trying to install the towing module on my 2014 q7. The wiring harness that came with the unit has 2 connections, 1 to the ecu module, then a second green block (see image). What does this green one plug into??

 

Did you buy the full Audi kit, or just doing it piecemeal? Reason I ask is the Audi kit has instructions, and the hard part, IIRC, was the ground wires connections and locating/recognizing the car's harness connection for the smaller connector (wrapped in foam and tucked in tight in the right rear).

 

It was a used kit I purchased from a junkyard on ebay, so no instructions. Anybody have some they would care to share? It sounds like maybe the connector is wrapped in some.foam? I saw one connector that was foam wrapped, but it was a smaller 2 or 3 prong, not large enough for this green connector.

 

The larger connectors go directly into electronic modules. IIRC, the large connector goes into the lighting controller box, and the smaller one goes into the other side of the stack that the light decoder/controller mounts on top of, there in the rear right side of car...it's all fairly close together in there in that back right corner. To see it all/access, you've really got to remove the hold-down/anchor cleats on that right side (front/rear), then pull up that long trim piece they hold down, so you can remove the side trim panel with the power outlet in it to get behind there, etc., as that's where you are working, and where the mounting bracket is located for the lights controller unit, which just snaps into place on top of the components 'stack' / tower, for lack of better term. I'm sure you can find same videos I watched on u-tube prior to doing this myself, and then it's just down to figuring how to best route the wires to get them where they need to go, and making really good connections on the ground wires to the car's ground points back there.

I removed the top layer of tire tools, those cleats/trim pieces, and pulled out the side trim panel with power outlet in it. Failing that, you'll be perpetually stumped, as you just can't see, or access it all.

 

You might also just want to make sure you got the correct harness, as it's basically the same style setup for all the Audi Q models, but they all have different part #'s, cable lengths, etc. for the individual models. A harness cable set from a 4M chassis, Gen 2 Q7, likewise, is unlikely to work for you in this 4L chassis...low hanging fruit to keep from wasting time, etc. I looked around a lot trying to find 'used' towing bits, and most of what I found was pretty sketchy from auto recyclers. I ended up just buying the OE trailer harness off eBay from Latvia/Lithuania...it was one of those places. Still overpriced for sure, but brand-new OE part, and considerably less cost that getting from a dealer. For me, it's a part I only want to install or mess with once, so buying one that came off an '07 was less than a 'sure-thing', even if it did save me a few $$ I did see there is one seller making 'homemade', but pretty high quality looking trailer harnesses for the 4L Q7at a price point around $180, but is hit-or-miss as they don't produce very many, and it's a high demand item.

Try this link and start at the top page, there are others similar to this out there:
https://www.audiworld.com/forums/q7-...2832192/page2/

Beware, the routing of the harness is meant to go up through the round hole (visible only from under car), which is located at the right-rear corner, bottom of the car, and up in a little recessed area just to other side of the muffler. I would not take out the car's air/exhaust vent, as is detailed in the official instructions, as it is a recipe for breaking old plastic bits you don't want to break/replace, but rather remove the interior trim pieces to gain the required visibility/access, as pictured in the linked thread. There is another round hole with a rubber stopper in it you will see from rear of car, which is not correct for trailer harness routing. That section at extreme right rear is where the harness comes up from bottom of car and has to be routed into different areas from there.

Hope this helps! There are plenty of other videos/threads w/pics posted on this topic.