So Im happily hooking up a 4 prong connector on my truck and trailer, then nothing trailer side. So i start testing the wires on the truck BEFORE the trailer connector, and no voltage reading anywhere..then all of a sudden my tail lights go out. Now, only the brake lights work on the truck but no back position lights. The 4 prong hook up came with those little clips that you just clip the new wires to the existing ones and a little blade clamps down to make the connection....help..seems i am slowly killing my truck by hooking up this trailer.
Thanks dudes.

 

just out of curiosity(sp) what year is your truck? When I had bought my truck(98 xlt scab), the stock hook up had been ripped out, i tried to use one of those kits for a quick fix and it did the same thing. I ended up just re-wiring the mess in my dorm parking lot like I should have from the get go. I dont know why those kits didn't work, ford didn't either. Check to see if your truck has a loose pig tail, or a ripped out rat nest looking thing under the rear. Mine was about 2ft back on the drivers side frame there was the split, it had all the wires for my hook-ups for a 7way plug. I hope this helps some, if not lets you know your not crazy and not the only one.

 

It's more than curiosity, we HAVE to know the model and year of your truck.

 

oh yeah...
its a 1992 F-150 xlt, someone put in a 5.8L instead of the 5.0L it originally came with, and repainted the body. A for effort, but a few things weren't put back together perfectly..like the door release mechanism on the drivers side...anyway back to wiring: I ripped off those stupid little connectors and reconnected them the old hand twist way... now all lights work EXCEPT those tailights!! I checked and double checked all fuses and just cant figure it out... i mean supposedly the same fuse does all those lights in the back so why are some working and not others...no, im not crazy but running out of ideas...

 

What are you using for ground to check for voltage at the trailer tow adapter ?

Are you sure it is missing voltage, not missing a ground ?

 

check filament in bulb?

 

If your connections are good, the fuse are good, and there is power at the connection, then I would highly suspect a bad ground or some how both bulbs went bad at the same time.

 

yeah, i drilled a new hole in frame for ground connection and it fixed all other functions, and bulbs are a combined function..so they work for signaling..im gonna replace fuses again and trynpushing em in harder...

 

thanks for the input guys
i'll keep you posted

 

Might not be much help but i have a semi similar prob only i know what i did, i have the round type connector i accidentally shorted it to my shell and lost turn brake and park lights to my trailer connector on the truck --found the fuse for turn and park lights but cant find the brake light prob by the way the lights on the truck itself never stopped working except for the third brake light above the cab my shell did not come with a third brake light so for the last 4 years i have just plugged a temp third light into my trailer plug until they required hard mount then boom checked all fuses checked all relays now i am looking for a fusible link F-150 1997 5.4 liter 4x4 there are 4 fuse boxes on mine one big one one small one and one smaller one under the hood in front of the driver side against firewall and of course under the dash good luck if i find what i blew up (perhaps fusible link?) i will post
Thanks
John

 

thanks...pretty sure i only have one fuse box...but im gonna double check that aspect, otherwise I dont know where the problem lies...also there are two brown wires which i cant figure out, coming from the same packof wires (green, white,black, yellow)