I recently purchased a 1978 Taylor 2 horse bumper pull. When I went to pick it up the guy had a three wire plug and loose ground hooked into his v6 f 150. I have a 1997 Lariat 4x4 that I bought an 5 wire to 7 wire adapter for thinking it would be able to accept most plugs that way. Upon hooking it up there were no lights on the left side of the trailer and everything else worked like it should on the right side. I pulled it home without a problem and then got a standard 4 wire plug. I thought i would just be able to replace the plug by matching up wire colors, but when I wired it up the same thing happened. So I bought a hopkins 4 wire kit and rewired the whole thing.

Now I have running lights on both sides, but the brake lights and turn signals don't work and, of course, no hazards - just solid trailer marker lights. I checked the plug for continuity and know the wires are solid.

I need to get this trailer working so my fiance can start trailering our horse to get ready for an up and coming vacation.

any help on this matter would be greatly appreciated.

Thank you,
Richard

 

Your tail lights on the trailer might need to be grounded. I wired up a flatbed I built and the tails I used had ground on them didnt think I needed it if I used ground on the plug but you do

 

both the trailor and the truck has to be grounded. most people think the trailor grounds thru the ball hitch, sometimes it will but not a reliable ground. the white wire in the 4 wire set up is the ground, find a suitable place underneath the truck for the ground. the ground wire can be attached to the tounge with a sheet metal screw. with a test light check the plug coming from the truck with the trailor connection un plugged, each prong should should light the test light when activated, such as left turn signal, right turn signal, and brake lights. the left and right turn signal prongs are also the brake lights. good luck

 

If you have running lights you have a good ground from truck to trailer. Using the test light work your way front to back. Most often your lights in the back may not have a good ground though. The bolts holding them to the frame probably provide the ground. Sometimes you need to run a ground wire from the front to the back to check the light out.

 

1997 Ford F-150 XLT 4wd---After taking a multi meter and checking the continuity of the wiring at the 7 prong connector on the truck and removing the harness also checking all the fuses I was frustrated. The brake lights and turn signals on the truck worked but not on the boat trailer. I read on other forums about different things but could not find the solution. It appears that the year and assembly location of the truck has great bearing on the wiring. It turns out I had a blown fuse but locating it was difficult to find. On my model, under the hood on the drivers side there is a large fuse box, all the fuses were good. To the rear of the fuse box is another box with relays in it and if you look carefully behind that mounted next to the finder is a small fuse box about 1 inch X 4 inches, I am trying to attach a photo, and in that box is two fuses, the 20 amp was blown and after replacing it the lights worked OK. That was 6 hrs. later. Good luck