Troubleshooting A Non-Working Running Light On A Boat Trailer

Updated 07/10/2024 | Published 07/02/2024

Products Featured in This Question

Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End

(111)

$14.52

30 ft. Wishbone 4-Way Trailer Wiring Harness with 30" Ground Wire

(9)

$18.82

Digital Multimeter with 42" Long Test Leads - LED Display

(3)

$21.72

Question:

New lights on boat trailer, driver’s side works great other side the running light doesn’t work but the turn and brake light works, changed out the bulbs and still noo

asked by: Paul

Expert Reply:

Hey Paul,

Stop/turn signal light functions typically use the same wire and the running lights are on their own. You'll want to go to the passenger side and check the running light wire for power with a multimeter # PT89ZR. If you aren't receiving power at the light then you'll trace that wire back to the power source looking for damage and checking for power until you find where it stops.

With this being a boat trailer I would typically just rip out the old wiring and start with new wiring # A30WB because a lot of the time the casing for the wires melts inside the frame and then the exposed wire shorts to the frame. You typically can't find the issue until you really rip it all out and with wishbone wiring harnesses being so cheap it's worth it to just replace it instead of wasting your time.

expert reply by: Kevin C

Paul

7/10/2024

Its all new last year

Kevin C.

7/10/2024

@Paul Did it work previously and then when you changed the lights stop working or has it never worked to begin with? If you're not wanting to replace the wiring then you'll revert back t tracing the wire with a multimeter and seeing where the power stops to find the issue.