Troubleshooting Trailer Wiring Not Working with 2015 VW Tiguan

Published 10/23/2018

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(135)

$77.56

16 Gauge Primary Wire - Black - Per Foot

(61)

$1.14

Hook Probe Circuit Tester

(61)

$13.33

Question:

I tested with a tester and all lights work per the tester, but I still not get turn signals to blink, is it possible that the car and the part on the car is not giving enough juice? The tester lights are bright so I want to think not but I checked my trailer lights for any issues and none show up, wires look good, should I just buy new lights and try them?

asked by: Michael R

Expert Reply:

Since you installed the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118675 exactly as shown in the attached videos, I recommend testing the trailer functions at the 4-way without the trailer connected using a circuit tester like # PTW2993. I've attached a video to assist.

If you are not getting the functions, I recommend first checking your ground connection to ensure you are getting a good ground. Often when one function works and others do not or if one function doesn't work and others do, it is a ground issue.

If you have the functions there, then I recommend checking your trailer ground connection at the main connection near the coupler if it has one or at the tail lights, which can ground through the mounting hardware. The connections need to be bare metal to metal and free of corrosion or debris.

expert reply by: Jason S

Michael

10/23/2018

Jason S.

10/23/2018

Before replacing lights, I recommend using a circuit tester like # ALL640595 to test your trailer light wiring. Make sure your trailer tail lights have a clean ground connection that is bare metal to metal and free of corrosion or debris. Tail lights will often ground through the mounting hardware, so you will want to make sure that is connected to bare metal as even paint can be an issue for a ground connection. Then use the tester to probe through the insulation on your wiring for the stop/turn function and test it. The turn/stop and hazard functions are all on the same circuit on the left side and are all on a different combined circuit on the right side. If you don't have the function on the wires, then you will need to check it every couple of feet to locate a short. Replace any wire with # 16-1-1 sold by the foot. If you want to check your lights, you can run a jump wire from any 12V battery to test the function. Don't forget to check the bulb too.