Boat trailer wiring/lights question

[COACH_EM_UP]

Just put some new taillights on the boat trailer. When I have the truck turned ON, none of the lights work. Brake, blinker, running light, or hazards. When I turn the truck off, all of the above mentioned lights work as they should. Turn igniton back on and lights don't work. Hooked up my lowboy trailer and all lights work, whether truck is on or off.

Is it the wiring of the boat trailer or something else? Any help or suggestions are welcomed and appreciated.

[BrandonH]

The first thing I would do it check the ground. Nearly every time I have trailer light issues it ends up being a bad ground.

[KY2TX]

I agree sounds like ground issue. I would start at the tail lights you added to see if they were made to ground thru bolt or wire that may have been tucked. Then ground at connector on tongue

[Sackett]

Assuming you have a “4-flat” trailer wiring plug:

ground would be my first check. If the lights you added are LED’s, each one needs the white ground wire attached to the trailer where the bolts that hold the lights on and make sure there’s a good connection with no corrosion. Then, I’d connect the white ground wire (assuming you have one) at the trailer plug securely to the trailer tongue.

When you checked the lights, has the trailer been empty or was your boat loaded on it?

[easeup]

It is the new LED lights. LED lights are probably wired with your 12v+ to their ground wire, & vice versa. it is like the chinamen dont know red is + and black is -. but to be sure of that.....disconnect the truck and run 12v+ to the LED and 12v - to the ground. My guess is they wont work. then switch polarity and check

[COACH_EM_UP]

Thanks for the help. The ground wire, in the tongue of the trailer, had split apart. Got it fixed. Appreciate the help.