jwilliams81

Hey everyone,

I paid a dealer to install the factory trailer hitch on our Q7.
The car is prewired for a brake controller, I was able to find the connector under the dash, so I installed this https://parts.audiusa.com/p/Audi_2015_Q7/CURT-TriFlex-Brake-Controller/73268506/ZAW055204A.html.
That Audi kit consists of the Curt wire harness (https://www.curtmfg.com/part/51522) and the Curt brake controller (https://www.curtmfg.com/part/51140)

I plug a tester (https://www.curtmfg.com/part/58270), I get the below dash warnings when I turn the car on:

• Trailer left rear light
• Trailer right rear light
• Trailer brake light

What could be the causes of this?
Here is a video of the warnings happening on the dash:
I have been trying to read about this issue but I am not sure what to do.
If the dealer did not recode the brake control module from ROW to USA, could that be the main reason of these faults?
Or is there a wiring issue with the brake controller and wire harness that I bought?
Or do I need to use a different brake controller and wire harness?

-Wes-

So, my first question is..... did you work with someone on the tester to verify whether the lights on that unit are coming on when called? In other words, you press the brakes, do they turn the tester light on? Left blinker.... right blinker, etc?

This issue could be something as simple as voltage. The warnings you're seeing are for bulbs out, and I get these same errors with my fog lights when I converted them to LED bulbs. If you have this tiny little tester plugged in, the vehicle may just think that the bulbs are out because the circuit is active, but there is not enough draw based on the programming. In the end, it may not be an issue when you have an actual trailer attached, or perhaps you just need to recode in the VAGCOM to not have the system test for these circuits. Because you're having anything happen, and it only happens with the tester in place, I'm hopeful that the wiring itself was done correctly.

4Driver4

I think it's the tester. These vehicles are a PITA with the voltage sensing parameters. Do you have a trailer to can hook up?

Not for nothing, but I don't like your controller mount. Not sturdy enough, easy to kick by accident, impossible to reach while driving.
Yes, I know there is virtually nowhere to mount a controller (why, Audi, why?). I had the same controller but replaced it with a remote **** unit.

-Wes-

I agree, @4Driver4 , but I was trying to focus on the immediate concern.

4Driver4

Definitely - was not trying to debate you at all...

jbgilbank

Never mind the carbon fiber wrap, went back to stainless! But this mount has served very well!

'10Q7TDI_Prestige'

Best test is to plug in an actual trailer to car connector. If the dealer didn't change the code for the added trailer lights module from ROW to North America, the marker lights on trailer function, but brake lights will not work.
If the tester is just little LEDs that have no load resistance built in, then the tester will cause car to throw out bulb-out errors, like yours is doing, etc.

It's one of those issues, and perhaps both of them. I can verify, having installed my own tow kit, that it will continue to fault and brake lights on trailer won't work if the lights module is not set to North America. Also, you will need the Curt LED adapter (Audi sells for $20, or can buy it less other places) if the trailer has LED brake lights on it...you want to plug trailer harness into adapter first, then plug adapter into the car's 7-pin outlet, etc. Be sure to read up and understand what safety features turn off or modify/change function when you plug in the trailer harness to car; that's important stuff.

jwilliams81

Ok everyone... I just took the Q7 to another independent shop near by.

After an hour they called me and said the dealer had not done any of the required reprogramming to tell the car the trailer hitch was installed.
They updated the software and charged me the minimum hourly shop rate.

Everything works as it should now, the little tester I was using causes no dash errors as it was in the video.
I'm a happy camper again. Still trying to decide if I want to battle it out with the local dealer and ask them to pay for the other shop's invoice. But for now I am happy.

Also, I do understand everyone's comment on the placement of the controller and the actual controller itself. I will keep that in mind for the next bonus check I get.

'10Q7TDI_Prestige'

Just to check understanding; there's nothing wrong with the brand/model of brake controller you bought. If you don't mount the controls for it for a natural reach, and easy access, regardless of the brake controller unit, then it's worthless to you in an emergency, or basically even to make simple, on-the-fly adjustments to the automated boost level preset, etc. You don't want to cause yourself an accident while trying to modify your preset boost level or add an extra touch of braking manually during a challenging situation. You just need to mount the control head to be accessible; treat it like your life depends on it, which indeed it may.