Trying to Install ZCI Circuit Protected Vehicle Wiring Harness on 2023 Audi Q7 with 5 Wires

Updated 07/04/2025 | Published 05/14/2025

Products Featured in This Question

ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit

(521)

$192.62

Hook Probe Circuit Tester

(60)

$12.27

Question:

Hello, I am installing the Tekonsha 119250KIT on a 2023 Audi Q7. I followed the video for the 2018 Q7, but it does not seem to be working. One notable difference, the wiring harness going to my tail lights has 5 wires, not the 4 shown in the video. The colors seemed to line up, but Im thinking I have the wires on the wrong leads. Is there an updated diagram you could point me to? Currently, using a tester, the tail light lamp stays lit all the time, even with the car off. The right blinker works, but I get nothing from the left blinker. Any help would be appreciated. Thanks.

asked by: Brian P

Expert Reply:

Hello Brian,

You're running into trouble with the Tekonsha # 119250KIT trailer wiring kit on your 2023 Audi Q7 because the tail light wiring is different from the 2018 Q7 shown in the installation video. Your Q7 has 5 wires going to each tail light, while the video only shows 4. That extra wire can make it harder to figure out which ones to hook into, and that’s probably why some things aren’t working right, like the tail light tester staying on all the time and the left blinker not working.

The Tekonsha kit uses sensors that clamp onto your car’s wires. These sensors "read" the signal going through each wire without cutting or splicing. For the system to work, you have to make sure each sensor is clamped onto the correct wire: one for the brake lights, one for the left turn, one for the right turn, and one for the tail/running lights. If even one is on the wrong wire, like one that has constant power, it can cause weird behavior, like lights staying on all the time.

Instead of going by wire color (which might not match the video), you should test each wire with a circuit tester or multimeter (like # PTW2993 ). For example, turn on the left blinker and see which wire gets power, that’s your left turn wire. Do the same for right blinker, brake pedal, and tail lights. Then clamp the Tekonsha sensors onto the wires you know are correct.

I do not have a wiring diagram for your Audi, I am very sorry. If you are still running into issues please let me know.

expert reply by: Kate F