Wires Melted and Burned When Connecting 5 Wires to 4-Way Connector

Updated 04/26/2018 | Published 04/25/2018

Question:

I have 5 wires coming off my boat trailer that i am trying to wire into a 4 flat to hook up to my truck. white, gr, yellow, yellow/brn, green/brn. I hooked white to ground and using info from your site, hooked yellow/brn and green/brn together and wired it to the brown wire of the 4 flat. i had not hooked the plain yellow or green up yet. i then turned on the lights on the truck to see if the running lights were working, and nothing. Except the wires melted and burnt in two. I checked the 4 flat off of the truck to ensure it was working properly before i did this also. Any suggestions?

asked by: Chris

Expert Reply:

A common problem with wiring is that there technically is no "standard" when it comes to the color wiring used. The typical colors and their functions are shown in the attached photo, but this isn't a rule. This means that anyone at any point in time can use whatever color they want for whichever function they choose.

Did you happen to test the wiring on the trailer before making your connections? If not that could very well be the reason why your wiring melted and burned. What you need to do is test the function of each wire by applying 12V of power to each circuit to see what happens. You can ground the negative terminal on the battery of your tow vehicle and then use the positive terminal to test your wires.

I have linked our selection of wiring and connectors for you to filter through as well as our list of trailer connectors like part # A35W42B if you are needing to change out the wiring on your trailer.

expert reply by: Jon G