My trailer lights do not come on when my truck lights are on. It seems to be happening only when I pull the boat with my truck.  Only the break, blinker and reverse lights work.  They work like if you were pulling the boat during the day with the truck lights on.  The side lights do not come on at all. A friend of mine pulled my boat the other weekend and all the lights worked fine  even the side lights.  They stay on like they should when traveling at night.  I looked at the fuses for the truck and they all look good. Any idea???

Check the ground between your truck and the trailer. Do not rely on the ball and coupler for your ground.

Some trucks also have fuses under the hood.

The side lights/marker lights should come on with the taillights.

Since it works perfectly on another vehicle, it has to be a problem in the wiring on your truck.

How old is your truck.  Is it factory wired for the trailer connection, or did you have it tied into your tail light wiring.

I just had a problem with my new truck, and found that it had two separate fusing systems for the truck and trailer wiring harness.

Check your owners manual for fuse locations.  My trailer connections were in a fairly large box with may other fuses.  The trucks tail light fuses are behind a panel in the cab.

Most trucks in the past five to ten years are wired to the rear bumper, even if they do not have the trailer package.  I would think that all factory installed trailer wiring would be separate from the truck.

You don't want problems with the trailer taking out your trucks tail lights and vice versa.

The lights were working before.   I have ford 2006 F150.  I thing my father tried connecting the four prong connection the wrong way and it made a short.  Any idea were I can find the trailer wiring fuse box.

I did a search on google about a fuse box under the hood.  I found the fuse box diagram and where i can find it.  I found the fuse box under the hood.  I checked out all the fuses and found one burnt out.  I changed it and fixed the problem.  Case solved.  Thanks for the great info Fishing Rhino and Team Dougherty.  CASE SOLVED!!!

the fuse could have blown because, one of the wires could have a nik in it and touching metal. hapened to me w/ my work truck. i kept blowing fuses till i patched the wire.

last time i had trailer lite problems i changed all kinds of bulbs,traced wires and checked grounds. it turned out to be the relay box,not the fuse box,on my nissan.Trace your wires from the plug on your truck back underneath the truck and see if you have some kind of box that your wires come out of.....