Troubleshooting 2020 Subaru Outback Trailer Wiring with Bad Running Light Circuit

Updated 08/04/2021 | Published 08/02/2021

Products Featured in This Question

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

(3583)

$40.45

Digital Multimeter with 42" Long Test Leads - LED Display

(3)

$21.34

Question:

The brake lights and turn signals work really well. However, the regular running/tail lights do not work. They haven’t worked on multiple trailers, including standalone magnetic lights. On my tester, the tail light indicator lights up, but it doesn’t drive the actual lights. Any tips?

asked by: Tristan D

Expert Reply:

It's possible that you've got a bad connection on the tail light/running light circuit, but I recommend that you begin by using a multimeter like the # PT89ZR to see what the output voltage on the circuit is at the plug. It sounds like you might be getting microvolts on the wires but not a full 12v, but the amount of voltage might give some clues as to what's going on here. If you've installed an aftermarket wiring harness like the Curt # C56040, then I also recommend checking the ground connection and making sure it is firmly secured to a paint, rust or debris free spot on the frame.

If you can check the voltage and also the owners manual on your Outback to see if there are towing related fuses in your fuse box that can be checked, and let me know what you find, I'm happy to continue assisting you on this.

expert reply by: Erik B