Trailer Lights

I hooked my boat up to the harness and the lights did not work. It is the 4 prong one with the one rubber one on the end. The Weird thing is if I cut my headlights on they cut on but none of the signals work and if you hit the brake lights nothing happens. I have no idea what is going on... Any suggestions???

Re: Trailer Lights

Get a $4.00 trailer light checker for the truck side harness and see if you have power to all lights(circuits); if you do then you have a poor connection in trailer harness or the ground wire (white) is not making good contact(probably).

Re: Trailer Lights

RiverLance2012 said:

I hooked my boat up to the harness and the lights did not work. It is the 4 prong one with the one rubber one on the end. The Weird thing is if I cut my headlights on they cut on but none of the signals work and if you hit the brake lights nothing happens. I have no idea what is going on... Any suggestions???

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If I interpret it correctly, you are saying that the Tail Lights are working but both Turn Signal/Brake lights are not!

Sounds like the Ground(WHT) and the Tail Lights(BRN) circuits are OK.

The Left Brake/Turn(YEL) and Right Brake/Turn(GRN) are not!

Each "Tail Light" Bulb on the trailer has 2 filaments in them.
The Brake Lights and the Turn signal are the same filament.
The Brighter filament is for the Brake/Turn Lights.
The Dimmer filament is for the Tail Lights.

Before you go any farther, make sure you do not have a burned out filament on both sides.
Being the brighter filaments, the Brake/Turn filaments tend to burn out first.
You would not be the first person to have 2 bad bulbs.
It is way more common than one would tend to believe.

Then I would suspect a bad connection at the Flat 4 connector.
Turn on your emergency/4 way flashers in the truck and start shaking wires to see if you can get the Bake/Turn light to flicker.

Re: Trailer Lights

by chance are you hooked into a suburban or tahoe? I had the same symptoms and it took a lot of people a lot of time to find out, that a white wire on the vehicle which everyone knew was a ground was actually an extra brake signal (like the one over the rear windshield) so activating the brake caused a short, but not enough to blow a fuse. I could do wierd stuff like make the turn signals work if Iturned off the headlights, etc.

So in addition to the bulbs, first get a tester to see if it's in the vehicle--they are cheap. But even testers lie (as I found out) so hook up to a friend's trailer, too, and see what's going on.

PS my vehicle harness was dealer installed.

Re: Trailer Lights

what kinda vehicle are you towing with ? yr/make/model.. and is the flat 4 on the vehicle AND trailer or just trailer?

and correct me if im wrong but sounds like you have tail lights on trailer but no turn or brake signals ?????????

Re: Trailer Lights

Thanks everyone, I finally found it. There we two wires pinched together which Im guessing was the brake and turn signal wires. They work fine now!!!