DUTCH VanAtlanta

There's a Euro setting and a US setting. I wonder if they had it first set to the Euro setting.

vr430

Hi, I did not want to start a new thread, but am having exact same problem.

I have been towing my boat for years, but picking it up this year from storage have run into exact same issue - Left Trailer Light and then Brake light out. Trailer lights themselves are fine, running lights, hazard lights, and turn signals all work off the harness, but not brake lights.

I do have air suspension. When I activate turn signals, dash shows not only regular arrows, but trailer indicator light blinks as well. This tells me electronics see my trailer. Actually, if it did not, it would not have trailer back light error on the dash. I did not check whether trailer shows up on MMI, but suspect it does.

The question is, what could have happened from one year to the next to suddenly throw things out of whack? And more importantly - how to fix it. I am out of warranty and hope I can fix this myself and avoid a trip to the dealer.

Any and all help is greatly appreciated. Thank You.

vr430

Okay, found this on another thread:

"the brake lights are a pulse versus a steady 12V."

This refers to European towing coding vs US. When I hook up a multimeter, this is exactly what it shows - voltage pulses. How the heck did my truck switch from US to EU programming overnight? I did not disconnect my battery. I did not have to jump start my car.

Does anyone know what codes I need to check/change? I have access to a VAG.

Thank You!

vr430

Self-Update

Yes indeed. Last March, we accidentally ran down the battery and coding must have messed up. We checked with VAG, and my trailer option was set to ROTW and not US/Canada. Once we fixed that, trailer light functions are all working normally now. Ross-Tech wiki is a wonderful thing!

j2nh

I just had this happen to me. Before you do anything else check the 20 amp fuses in the back of the vehicle. For reasons unknown I had a fuse blow for the left trailer lights and it was giving me fits, because the MMI was stating the fault was with the left trailer lights I spent hours checking grounds and lights only to find out the fault was a blown fuse.

Savior Six

Marioec, or VR430,

This applies to anyone that has had their trailer hitch problem resolved by the dealership. Can you tell me exactly what parameter was incorrect with your vehicle? I'm having the same issue, my trailer is hooked up to my Q7, all the lights work except the brake lights, and I get the brake light faults on the dash. I do not have air suspension, or backup camera.

My local Audi dealer is telling me if that if installed the Audi OEM trailer hitch kit which include the trailer control module (which I did) it should be plug and play, technically it was plug and play but as we all know, there has to be some coding updated to get this to work right. If anyone can provide the exact parameter that was changed with a Vag Tool to make their trailer work correctly, can you please post it. I have the info off the Ross-Tech Wiki page, but I just want to go to the dealerships with possible solutions (basically doing their job for them) so I can get this resolved.

Any help would be greatly appreciated.

marioec

I wish I could help you but it took 3 trips to the dealer for them to figure out the problem. Take it to a competent Audi Dealer and talk to the servise manager.

Savior Six

Finally got it fixed!

After two trips to the dealerships, they finally got it right. This time they had my Q7 for three days. The service department was pretty busy this week, and they gave me a 2011 Q5 courtesy car so I was ok with my Q being gone for so long. I just wanted to post my fix action to potentially help anyone else that is having this issue. The fix action, per the work order:

"Checked and found coding was set for mechanical/lockable hitch. Set for USA/Canada/Mexico (I guess mine was set for RoW - Rest of World) Performed ZUG update and SVM for trailer hitch. Tested system and it is operating normally"

As soon as I got home, I hooked up my Kendon motorcycle trailer and everything tested good.

Hope this helps anyone out there that is experiencing the trailer hitch brake light failure. it should be noted that I did not bring my Q7 to the dealership with a trailer hooked up, but I did print out the notes from the Ross Tech Wiki site to assist them in trouble shooting the problem.

vr430

Audi Q7 (4L)
Menu [69] - Trailer
Coding: 0000002 For USA/Canada

That's it. That is all you have to do.

If you have air suspension, backup camera, there are other codes to check. In my case they were all fine. Trailer country code was the only one that was reset by a rundown battery condition. Go figure.

jeolesen

I have a 2014 Q7. Trailer hitch installed from Audi.

Most lights work fine when I hook up the trailer (blinkers and driving lights).
But the break lights doesn't work on the trailer.

I have read that I may need an update to the trailer settings on the cars computer. Specifically I have read that I should get Audi to check this:

Audi Q7 (4L)
Menu [69] - Trailer
Coding: 0000002 For USA/Canada

I do not have air suspension, but do have a backup camera.

Are there other codes in the computer that need to be verified/changed ?

Thanks in advance for your help