Dr Chill

The trailer has electric brakes but I don't have an electric brake controller. Do I need one?

Double_Dip_A6

Probably not needed but I would recommend since you are approaching 80% of the maximum towing capacity. Also depends on how far and where you are towing. If you are going a long distance and have much hilly terrain then I would definitely recommend.

If you have never towed with electric brakes before it takes some getting used to.

AC S4

but I can't imagine how the cops would find out. That said, I personally would not tow that heavy a load without trailer brakes.

On a related note, I checked the wiring for the factory tow package and it has 7-wires. However, I tested for power on the electric brake pin and there was none when the brakes were applied. I suspect that the Q7 is pre-wired for an EBC but nobody seems to know where to find the other end of the harness. I've inquired with my dealer and they haven't gotten back to me. I plan on digging under the driver's side dash to look for the harness.

Dr Chill

Believe it or not, someone who purchased a Q7 with the "tow package" might want to do something novel and actually tow something with electric brakes. They apparently made running changes to the wiring harness to allow installation of an EBC but they have no way to tell if my vehicle has it. I guess someone at the plant forgot to write down the VIN where this change started. As soon as they can get the engineer to check out my car, I'll post their answer. For now, I'll tow my race car on a Uhaul trailer with hydraulic brakes. Funny how the main reason I bought this vehicle was to tow my trailer in style. If the dealer wants to charge me a fortune for this, I'm going to blow my stack!

AC S4

Do you have to pay for this inspection? Why can't the dealers do this?

Inclined

Owners were out 6-8 hours labor ( 500-1000 dollars ) to pull the interior to run a couple bucks worth of wires to the front for an EBC. They were pi**ed to discover this. Even the cheapest American trucks do it right with proper prewiring for EBC. Strange .

Inclined

There must be a reason all the SUVs /trucks at Lake Tahoe towing serious boats are American brands with big diesels or big V8s which can tow 9-12,000 lbs. The euro SUVs are maybe a bit " delicate " for the duty , where their advertised 6600-7500 capacities are really pushing the limit .Note the GL comes with "trailer stabilty control" logic where the ESP/yaw system keeps it all from going out of control , but I suspect that only activates in extremis during a heavy crosswind on a rain slickened ,curvy mountain pass !


From mbworld :

" After spending over $900.00 to get a brake controller installed so that I can pull a trailer weighing 6,200 lbs (well under the 7,500 lbs towing capcity that Mercedes Benz claims the GL will tow and is rated for), I'm quite dissapointed. Although the power is there and the braking is fine, the weight of the trailer makes the GL feel totally unstable. The trailer pushes, pulls and sways the GL in all directions and make you feel like the trailer is in control of the GL. I hooked up the trailer for a test drive before leaving for a 1,000 mile trip and quickly realized that I was not going to be driving the GL on this trip. The ability to tow 7,500lbs was a deciding factor in our decision to purchase the GL. Also the fact that they are not prewired for a brake controller is a joke. Advertising a 7,500 lbs towing capacity, sooner or later someone is going to hook up a large trailer with no brake controller installed and end up in a terrific accident. If you are thinking of buying a GL and have in mind towing a 5,000 lbs or heavier trailer, I would suggest you try it first."

Dr Chill

containing his Porsche. He had an EBC installed at a trailer place in Orlando for under $400, and that included the $200 controller. The tech doing the install had never put one in a Q7, but he said it was similar to a Toureg and was no problem. He also said his 3.6 had no problem pulling 4500 lbs.

Now let's see what Audi says after they inspect my vehicle.

DancerDawg

If you VIN is later than _7D021937, then you should be wired for trailer brakes. There is a 4 pin male connector under the driver's side lower dash. You need to get from Audi the female connector and 4 male pins to hook your brake controller to the wiring harness.

Your dealer probably installed the 7 pin trailer connector... it comes with the ball mount. If not, then you have to get it.

Audi has a TSB for Q7 trailer brake wiring. Email me if you're interested...

AC S4

Thanks very much! YGM.