Troubleshooting Trailer Tail Lights That Stay On with Tekonsha ZCI Wiring Harness on 2016 Golf R

Updated 09/14/2025 | Published 08/07/2017

Question:

After installing and troubleshooting using an expert reply on this isuue the fact that the tailights stay on when the car is off, I can say the following: -when I program the car with the headlights OFF, everything works fine -as soon as I the AUTO position for my headlights, afterwards the trailer tailights allways stay on, even when the car is turned off and locked. It seems to me there could be a bug with the module and automatic headlights. Do you know of such an issue? As long as I dont use the AUTO function, the tailights turn off when the headlight switch is off and they turn on when the switch is on. Also, do you know if there are issues with the come home function, where the headlights stay on for a specified period of time after turning the car off? Thanks!

asked by: Gab

Expert Reply:

We know from Tekonsha training on their universal-fit ZCI Circuit Protected Vehicle Wiring Harness # 119250KIT that this item is very sensitive to the initial setup process, which must be followed exactly for correct operation.

My technical contact at Tekonsha advised that the magnetic sensors in this kit are directionally sensitive. If one of these were clamped on in reversed orientation it would not function correctly. He suggested that you pull the fuse to let the circuitry power down and then try reversing the orientation of the running light sensor.

My contact had no information concerning the 'come home' lighting function.

expert reply by: Adam R

Bob R.

8/8/2020

I have a similar problem. I installed the ZCI in my Audi Q5 about 3 months ago and everything worked as it should except I always felt that I was not getting full power to the 7 PIN connector as I had to set my Curt Echo to the highest setting in order for it to work. Then this morning I hook up and all of a sudden I have to turn the Echo way down to keep from locking up the brakes. I also notice that now my trailer running light are always on whenever the 7 pin connector is plugged in. The brakes work better now but don’t really want lights on all the time. All other lights ( stop, and turn signal work fine.

Jon G.

8/18/2020

Start off by checking both your vehicle side and trailer side connectors for any debris or corrosion and clean out accordingly. If those look good then I would make sure that you are plugging in the Curt Echo # C51180 to your vehicle and then the trailer into the Echo. Some people have tried plugging the trailer into the Echo first and that causes problems for some reason. If that doesn't fix it then I'd start checking your grounds for your trailer brakes and your tail lights. Let me know if none of this works and I can see if there is anything else for you to try.

Marty

4/13/2024

I have tried correcting the same issue as the tail lights on trailer won't shut off. I'll pull the fuse for the controller and wait 10 mins and Reinstall fuse and lights stay off for couple mins and then back on. 2013 audi q7 is the vehicle and no lights selected on and veichel power off other than the power supply to the controller. Signals work proper. Tried orientation of connectors for the pickups and didn't make a diffrence. I also disconnected all the sensors and spaced out from any wiring and still turns on tail lights after couple mins of being powered.

Drake

6/15/2024

@Marty did you ever get this sorted out? I installed the ZCI in my 2016 Macan and can’t get it to work properly. Lights always on, go off when I press the brake pedal. Very frustrating. Thanks.

Greg P.

8/29/2025

The most frustrating thing—tail/running lights off for a while, then on by themselves with no way to turn them off but pull the fuse. 2016 MBZ Metris passenger van and 2017 NuCamp T@G XL teardrop trailer. All light functions are normal on Metris. Wire in the Tekonsha ZCI module, run through “Learning Process.” Test with Metris—works fine. Shut everything down, restart, test with Metris—works fine, all functioning properly. Shut everything down. While putting tools away—running and tail lights are on on the trailer! Touched nothing, the lights just turned back on magically. Got tools back out. Went through this process three times, before calling trailer. “We’ll check into it and get back to you,” they said. Came to this forum to commiserate. Anyone have any ideas? Rewiring hacks? Did I miss a ground or connection? How do I stop this unwanted fantom power running through the system?

Jon G.

8/29/2025

@GregP Wiring issues are the absolute worst. The instructions said to redo the learning process if you're having any issues. I know that's not what you want to hear, but the only other thing I can think of is that your trailer might have LED bulbs and some power is somehow still getting through to them. Another thing I recommend trying out is connecting your Metris to another trailer to see if this problem exists with that trailer as well.

Greg P.

9/2/2025

@JonG, I've tried redoing the "Learning Process" probably ten times--no success. The bulbs are standard filament bulbs, not LED. I do not have another trailer handy to try it out on, or I would have. The phantom power does show up on the wiring tester that is included in the wiring kit, however. I'm going to need more help from you guys, please, to find a solution for this trouble.

Jon G.

9/9/2025

@GregP I reached out to Tekonsha but they still haven't gotten back with me. Normally when we see this it's because some power is "leaking" through to the trailer and the trailer is equipped with LED lights (which don't need much power). Since you have incandescent lights, it makes this whole situation just really weird, and I'm honestly not sure what's going on. Try using a different trailer to see if the same problem comes up (I'm sure a local shop or trailer sales company would let you hook up the electrical), and if it does then we can be confident it's on the vehicle side of things, and you're probably looking at a new wiring harness. Since this has a 1-year warranty it would likely be something we can swap out for you, but I'll have to send this over to our customer service team if that's the case. Try testing the wiring out with another trailer and then let me know what happens.