Trailer Running Lights Dont Work But Brake And Blinker Lights Do

Published 11/19/2019

Question:

The new trailer lights work for blinkers and brakes. The running lights dont. Can there be a connection problem with the new lights if I didnt remove something when I put them on from the package?

asked by: Tom W

Expert Reply:

This is a regularly seen issue here because the running lights are on a different circuit than the brake/turn signals. It's important to first determine if the issue is at the vehicle or the trailer side. I'm gathering from your question it's the trailer only that has an issue with the running lights so I would start there. If you're not sure, the included Help Article describes in detail steps for sourcing the cause between both.

A place to start troubleshooting is to take the ground for both running lights and run a jumper wire up to the main trailer ground as this is the most likely the issue. If the running lights still don't work once this is done that leaves two other things.

Next check to see if the vehicle's trailer connector has power on this circuit. If not then you have a bad fuse. If however it is working you have an issue with the wire associated with this circuit on the trailer and you will need to start tracing.

expert reply by: Patrick R