DelgenQ7

I have a 2007 Q7 3.6 that wasn't pre wired for the towing option. Went with a Curt hitch with a Tekonsha P3 brake controller. Had to pull a separate two conductor wire for the curt taillight wiring adaptor and dedicated power to the 7 pin adaptor. The curt taillight adapter works flawlessly with low amp draw, so's not to confuse your system for a burnt out bulb. Found the 4 wire adaptor under dash to tap into brake signal which lead to rear compartment. One of the things missing from the tow package is the additional tow module that sits next to the lighting/comfort module . Wasn't about to pay $1000 for a tow module, and a wiring adapter, so that's why I went with the curt taillight adapter and with a little troubleshooting, taped into the tailgate wiring. The The q7 is special, because once the tailgate opens, the brake/signal lights switch to the lower rear valance for signaling of lights. I cut out the lower panel around the hitch to fit for a near factory appearance. This also hides protects the 7 pin adaptor. The panel is easily removed and stowed in the hidden floor compartment. From what I can tell from the parts sku, there is a bigger radiator fan, but all other parts (radiator, trans cooler) seems to be similar. I'm pulling a 20' travel trailer 4500lbs up and down the sierra's and the temp gauge on the radiator never moves from warm. There's more of the lack of power( torque )from the engine, but nothing a little sport mode can't handle.

malibu111

Interesting point made about the voltage change when hatch is open. I just purchased the Curt hitch and installed. The Curt tow plug 56200 NOT so good. The only way to identify where to splice in is from a U Tube video and that didn't go as expected. I did wire up per the video with the back hatch open. The video does reference a 2011 Q7 and I have the 2007.

I need to find the exact pins for attaching to the back harness. Power brakes option no a concern and no camera or backup sensor. After following the video the turn signal appeared to work but the stop and running lights didn't work correctly. I used a probe and verified wiring but NOGO. Has anyone dealt with the Curt 56200 and own a 2007 Q7 4.2?

aqaqaq123

Agonized over the same recently. The best OEM option I could find was some $750 online for the hitch + wiring package + $500 for the installation. Having read extensively on what the installation actually entails, I was going to buy an aftermarket Curt and install it myself. Tired of trying to find time for it, one day I said screw it, pulled into the local U-Haul and after a chat with the hitch dude (making sure he knew what he was talking about) I handed him the keys and one hour and $350 later a I had a hitch installed.

I did not care for the electronics because all I wanted was to carry bikes, so I did not bother with the wiring. If I planned to tow anything, I'd have bought an aftermarket module from Europe (whatever Audi sells seem to be rebadged Westfalia components, you can find them for decent money in the UK).

Not that you care but the tow rating on the U-Haul hitch (from the looks of it, it's a Curt) is actually 500 lbs higher than on the OEM one (it looks a bit beefier than the OEM too). The rating is entirely irrelevant i.m.o. as you probably should not be getting close to the max rated weight anyway because of the panoramic sunroof.

My hitch sticks out more than the OEM one by about half an inch. For my use case that's actually desirable and for a Saris Freedom or such it's definitely preferable.

malibu111

Recently purchased a used 2007 Q7 and plan to tow. I've had many tow vehicles in the past and wow, these SUV's are crazy complex these days.

This is what i found,
1. Some of the Q7's come with the tow cable installed, this is the one that runs from the front to the back and terminates a big RED connector at the back in the electronic bay. This is for the tow controller (4E0-907-383E) module. IF you don't have the module, which is my scenario, I need to purchase so the car know towing is active and provides the necessary feedback to the system. This module accepts the cable connection from the OEM hitch. Here's the key, when you purchase the OEM hitch, you get the circular external connector and nice harness which terminates onto the controller which completes the system.

2. Now, if you plan to run power brakes on your trailer, I believe you must have the factory cable which runs from the front dash back to the controller. This is where the early 2007 may not have this cable. I believe you may be Sh#t out of luck in this scenario. I have the RED connector but I don't need power brakes as I'm not planning to tow more than 2K lbs. Just a couple quads or my Harley.

I installed the Curt hitch and which is very strong and heavy but here's the gap, I need to the OEM cable harness which runs from the tow hitch and attached to the controller. I believe this can be acquired via the Audi OEM 500.00 hitch.

I purchased the Curt 4 prong cable harness, (56200) unit and attempted to splice into a connector identified by a You Tube video and that din't work as expected. Curt actually shows a (56200) cable harness on their web site and the picture shows a white connector on the end which looks like it may attach to the module. Need to confirm with a call to them today. Not very helpful unless I get a technical guru on the phone. I was hopeful with the Curt cable harness as I had a 12 volt probe and was picking up the turn signals but the park/brake light were displaying weird results. The harness I purchased has the Pulse module and I installed per a You Tube video per a 2011 Q7 model. Mine is a 2007 and the pictures didn't match with my electronic bay exactly.

I'm currently looking for a harness only and need to purchase the brake control module.

Any insight would be most appreciate.

aqaqaq123

Not 100% certain but from my research into this it would seem you need 2 separate components, the trailer module and wiring (such as this: http://www.auditowbars.com/audi-q7-1...500300113.html) and eventually a brake controller (Tekonsha or such).

I understand the car's electrical infrastructure is largely digital and the trailer module converts the digital signals from the bus it plugs into, to analog signals that are directly usable by a trailer. The module referenced above is plug and play whereas whatever Curt sells seems to be analog and you splice into the wiring of the tail lights to take that signal to the trailer ... quite a hack job. The proper digital module would also give you the ability to recognize that a trailer is connected and it would turn off the rearview camera and beepers (VCDS needed to activate features).

If you tow anything substantial you need a brake controller. Not sure where the threshold is, I'd like to know myself, 2 klbs sounds borderline. The brake controller is supposed to be connected somewhere under the steering wheel and your car would have to have the necessary wiring as mentioned above. I was told that all newer cars have it.

The level of obfuscation around what should be a stupid-simple issue like this really pissed me off when I did my hitch ...

dukesean

Maybe you can check this for some more ideas.

https://www.audiworld.com/forums/showthread.php?t=2692144&page=4


The red connector has 2 lines going into a black 4 pin connector and other 2 lines are coming from hitch. Then this 4 pin connector will plug into the cable that runs to the front dash. Some '07 owner found the connector didn't plug into the cable in trunk area. So that's easy to fix. Some like mine didn't have the cable at all like you mentioned. I have to remove rear bumper to find the connector from hitch, and the connector from red connector in trunk area ( both have 2 lines), then make the my own 4 lines cable all the way to front dash. I used oem connectors so it would looks like its from factory. I got the ideas from touareg forum as they got same problem for wiring brake controller. And some helps here from giblet.

Edd W

Not easy, the tail light swapover from tailgate to bumper is tricky to work round.
I would just buy the Westfalia kit -
http://www.ebay.co.uk/itm/AUDI-Q7-20...item58af3ddf0b

This will sort out everything you need as well as the coding changes. I fitted a bar from TowTrust which are made at a factory near me - they may well ship to the US -

http://www.tow-trust.co.uk/towbars/a...-in-the-bumper

malibu111

Call it a hack job if you like but here's the simple installation if you don't have the camera and safety backup indicator. After a lengthy investigation, this was my working end solution.
1. Purchased Curt hitch, $156.00 to the door and installation.
Remove back bumper screws, both underneath tail section and under wheel wells. Make sure you find all (5) on each side by tire. Make sure you find the one hidden behind the felt wheel well liner. Prepare to pull hard to get the side end-points off.
2. Purchased the Curt C56200, $80.00 wiring harness. You need to PWM type because the brake and running lights operate from a single wire connection.
The key here is to identify the signal wires from the tail gate light assembly NOT the electronics bay. I did tap into electronics bay for ground in the rear right side and found a constant hot wire on the 12 cigarette adapter at the rear and inline fuse at this point. The Q7 has separate light assemblies which operate active/passive. When tail gate is open, lower bumper lights are active and when hitch closed, tail gate lights operate and bumper go passive state. You must probe for blinker and running/brake lights on the tail gate assembly with the door closed. Yes, you need to get in the back with the gate closed and probe like I did. I purchased a $6.00 12volt probe tester from Harbor Freight, love that place.
Driver side tail light connector, pin BLUE- RED stripe (L-Blinker). I tapped this wire and ran across tail gate and down into electronic bay to C56200 module.
Passenger side tail light connector, same as other side, pin BLUE- RED stripe (R-Blinker). I tapped this wire and ran extension wire down to the electronic bay to the C56200 module.
Stop and Running lights provide (2) hot wires on each side in the tail light section. You can tap any one of the four wires as they all operate the Stop running lights. Why you ask, because there are two main tail light BULBS on each side. I tapped into the one on the passenger side as this is closer to the electronic bay. Neatly route the wires alongside the factory wire harness.
Ok, I now have three wires to dress down from the tail gate into the electronic bay and attach to the standard trailer wires, Green/Yellow and Red. Follow the color codes in the harness directions.
The tail gate cover can be challenging but here’s my method.
1. Remove the small plastic strip at eye level at the top roof line first.
2. Remove the two upper side plastic strips close to the roof line next; they overlap one another at the edges.
3. Remove the large tail gate cover
a. Disconnect the small interior light assembly, pops out by rocking socket…use caution…gentle
b. Remove tailgate button in the same manner as above
c. Remove screws in tailgate and there is one in each tail light section
d. Pull and detach heavy interior cover plate
e. Tap into necessary wires, use type wraps and do a clean job
f. Put all panel back on after testing
4. Testing and flat 4 ping connector goes as follows
a. With my probe, I attached to body ground and probed the 3 female leads in the plug
b. L - blinker should flash on one pin only
c. R - blinker should flash on one pin only
d. Stop - blinker should flash on all pins
e. Flashers and running lights on, all flash and blink on respective side
I never had to address the front of the vehicle. The only activity in the rear electronics bay was a self-tapping screw for ground and borrow the cig-lighter constant hot lead.
My 4 flat pin is now in the rear tray and I plan to drop it out the tail gate when needed. You can route the harness out the one and only rear rubber grommet which is literally buried in the back right corner behind electronics.
If you want to go all-out and require power brakes and have the camera and backup sensor systems, you need to get your wallet out and purchased the control module which would installed in the electronic bay. The right rear bay on these vehicles is full of harnesses and various module and for your spending pleasure. The fully loaded Q7’s need to provide feedback to the computer system that I have a tow behind me and disable camera and backup sensor system. In addition, the vehicle adjusts suspension and puts you in tow mode. Basically, you are telling the vehicle to adjust as soon as you attach the harness.
The OEM hitch is a NO brainer, double the price for Curt, which is nice by the way…pretty damn heavy. The only advantage to the OEM towing harness is the exterior receptacle is attached to the hitch and the harness is dressed through the side rubber grommet and then snakes into the electronics bay and attached to the control module. Simply attach tow trailer wire and a feedback signal talks to the vehicle and sets up the suspension and disables the necessary caution systems.
The only drawback is that the OEM system out of the factory is very expensive.
I wouldn’t be surprised if you could disable these nice features when towing by removing the fuses that run them and go the cheaper route like I did. All said and done, I spent $240.00 for my attachment.

Edd W

That is a great writeup and similar to what I did on my wife's Touareg.

The only concern I would have is that the rear upper/lower light control switches to the bumper lights if it detects a failure in the tailgate lights - does this seem to work alright when you trailer lights are connected or does it switch over as if there is a fault?

malibu111

You probably addressed the only question possible from my write-up. Good for you and my response would be to ask the engineers whom designed the computer monitoring system.

I would think that as long as the circuit leg continues to draw current to the right or left side, there should be no fault drawn. I may loose a trailer bulb but the auto tail bulb is still drawing.