Troubleshooting No Stop or Turn Signal on One Side of Trailer

Updated 02/13/2023 | Published 02/10/2023

Products Featured in This Question

Triplex Wire with Grey Outer Jacket - 14 Gauge - Black-Green-White - per Foot

(6)

$3.68

Deka Heat Shrink Butt Connector - 16-14 Gauge - Nylon Insulation - Blue - Qty 5

(1187)

$8.90

Question:

Hoping I can get some expert advice on my trailer lights. All the back and side lights work but I have no turn signal or brake on one side. I do on the other. Its an aluminum trailer with wiring in frame. I have checked everything I know I can. The bulb, the wiring, the truck fuses, etc. I cant figure out why I dont have brake or turn on one side. Any help would be appreciated. Thanks

asked by: Trent

Expert Reply:

The first thing to determine with troubleshooting wiring is where that signal is lost. If it's on your vehicle side then it's a fuse or bad wiring somewhere but if it's on your trailer side then it could be a bad bulb, light fixture, or the wiring itself.

If you've tested everything but the physical wiring running inside your trailer frame then that's likely where the problem lies. Somehow that wiring got corroded or damaged and is keeping that stop/turn signal from operating properly.

To remedy this you'll need to find the bad part of wiring and replace it using new 14 gauge wire, part # SWC5362-1 sold by the foot, and I recommend using Heat Shrink Butt Connectors # DW05744-5 to give you a better connection. If you're unable to gain access to that wiring then you might consider running a whole new line from your trailer connector back to any lights on that side of the trailer connected to that circuit.

I've attached a few review videos as well as a wiring page with some diagrams for you to check out.

expert reply by: Jon G