Testing Trailer Wiring for Function to Troubleshoot Both Blinkers Turning on at the Same Time

Updated 08/09/2010 | Published 08/05/2010

Products Featured in This Question

Optronics Combination Trailer Tail Light - 6 Function - Incandescent - Red Lens - Passenger Side

(1310)

$5.51

35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

(872)

$29.90

Hook Probe Circuit Tester

(70)

$13.12

Question:

which wires go to the correct wires on the trailer lights. I tried doing the lights last night and when I got the right turn signal to finely work the left signal come to.

asked by: Duane h

Expert Reply:

On the Trailer Stop, Turn and Tail Light, 6-Function, Right Hand, # ST8RB, the back is labeled, the brake light and turn signal wire (usually green) goes in the left connectors. The taillight wire (usually brown) goes in the right connectors. It sounds like the right turn signal wire is somehow connected to both turn signals.

If your trailer wires have different colors, or the colors do not match the functions described above, you will need to use a circuit tester, like # PTW2993, to find the functions of the wires, and then connect them to the correct ports on the trailer lights.

I have included a link to a video on replacing trailer lights below. In the video, the installer also changes some wiring. This is beneficial because the colors and functions will match what the majority of trailers use.

I have also included a link to an FAQ article on trailer wiring. The colors represented may not match what is on your trailer. It you are interested in wiring your trailer to match the diagram, it would help troubleshooting in the future. You could use Wishbone 4-Way Trailer Wiring Harness, # A35W42B.

expert reply by: Michael H