I push my brakes and the trailer lights go off?

Question

I bought a used 1990 14' fishing boat and the lights have never been right. so I purchased brand new brake lights wires and all. Everything works, but if my driving lights are on and I apply the brakes, the brake lights on the trailer go off. I dont think that is right. any advise will be geratly appriciated. thanks.

Answer 1

weak ground.

strip about an inch of insulation off the white wire on the trailer side, loosen a bolt on the trailer, wrap the wire around and tighten it back down.  needs to be an unpainted rust-free spot.

You can confirm my diagnosis by connecting the vehicle frame to the trailer frame with a jumper cable.

Answer 2

bad ground wire!

Answer 3

The tail light bulbs have two filaments.  It sounds like you have them wired in reverse.  The driving light should illuminate the small, less bright filament.  When you apply the breakes then the brighter filament will illuminate.  Make sure the trailer is the ground (negative) for the lights and that the trailer makes a good electrical connection to the car.

Answer 4

been here dun that .these r all good answers but the ground can be shoting in the light sockets or how they mate clean everything really good.

Answer 5

If you are positive everything is wired correctly, you are not getting a ground connection. If the ground wire is not in the trailer/ car connectore, the towbar/ hitch is expected to provide the grounding. Most of the time, this doesn't happen.

The reason the lights go off is the difference in power between turn/ brake bulb filaments, only the smaller power filaments will light (badly), as they "find" a "ground" path through the bigger power filaments.

Answer 6

I've seen this before.  If your car, has yellow turn signals you need an adapter to correctly hook-up the trailer lights.  they are common at trailer rental places and most auto stores.  It's also possible that the trailer is not grounding properly.  Drive around the block a couple times and see what happens.

Answer 7

There are two things that could be the problem- a bad ground, or the wiring is hooked up incorrectly- but there could be a third reason- if you have a Toyota vehicle, it requires an adapter to hook up trailer lights- purchase at a parts house or dealership. Good luck!

Answer 8

It sounds like you have bad bulbs, a disconnected brake light wire, or it simply isn't wired right to begin with...Have someone step on the brake pedal while you find the brake light wire...check the connection, if it still doesn't work, check the ground wire...it's got to be hooked up to a solid chasis bolt, or s***w...on the trailer frame, and the truck.