On my 1998 F-150 I am trying to figure out why my turn signals and brake lights don't work on my trailer when plugged in. All connections, grounds, fuses and relays seem to check out. When I check for a voltage signal on the turn signals and brake terminals on my 7 pin connector on the truck, should I get a blinking voltage signal from the turn signals? Or is there a certain way to check it? Because I have no voltage on the connector terminals from the 7 pin nor directly from the wires from behind the 7 pin connector which eliminates the pin connector from being at fault. I have turn signals and brake lights on the truck itself plugged to a trailer or not. But none on the trailer. I do have tail lights on the trialer. But thats all! Can someone help me out Please?

 

Do you have these colored wires at the back of your truck? Look at this post.

https://www.ford-trucks.com/forums/s...hreadid=147123

 

Yes the color codes are the same as that on the post. I know of the relays under the passenger side oval cover on the dash. All the relays and fuses check out good. One odd thing is, is that on the blue wire "Brake lamps" rises slowly. What I mean is, is that when the brake pedal is pressed, and I put a tester to it, the tester light starts off dim and then rises to semi bright. I've checked everywhere for a loose ground but I couldn't find one. The harness from the pig tail runs along the frame and then winds up under the hood. From there it splits off in different directions which stops me from testing any further because I don't know what wire is what! So if you can help any more, I would appreciate it!

 

"What I mean is, is that when the brake pedal is pressed, and I put a tester to it, the tester light starts off dim and then rises to semi bright. "

Do you have a trailer brake controller under the dash? That's what the rising voltage sounds like-the wire that goes to the brakes, not the brake lights.

 

Are the brake lights activated by the turns (Green and Yellow Wires)? Because I did figure out that the Blue wire is the e-brake wire. So I guess that works. It would make sense if the turns were are in relation with the brake lights. But how and where?

 

Check out this link

http://homerwinzlow.clubfte.com/

Click on the three trailer jpg to find common wiring schematic for the trailer.