How To Choose Correct Replacement Trailer Wiring Harness for a Boat Trailer

Updated 08/12/2020 | Published 08/10/2020

Question:

I installed a new passenger rear light on my boat trailer and after it was installed, all the functions worked great. I took my boat on the water and when I got home, I noticed only the drivers rear light was working. Now, a few days later, the blinkers for both rear lights work but the brake function isnt working. Im fairly sure all the wiring connections were tight and sealed correctly. Any idea what the problem could be? Im also considering rewiring the entire trailer and if I do, how do I know what wiring set to purchase? My boat is 20.

asked by: Nate P

Expert Reply:

In order to choose the correct replacement wiring harness for a boat trailer you need to know two bits of information, the length of the trailer and type of trailer connector used. If it is just a standard 4-pole then you can use the 35 Ft 4-Way Trailer Wiring Harness part # A35W42B which can be trimmed down if needed.

In regards to the trailer lighting issue, this is most likely caused by a short or a loose connection so you just need to start checking and tracing wires both at the tail lights and trailer connector.

expert reply by: Conner L