I do not understand what is going on with my trucks 7 pin connector. I have tested each pin by the ohm meter with someone in the truck working brakes/blinkers. It does not make sense. I had to put a new connector on my horse trailer. The problem is, the wires broke inside the trailer's connector so I can't tell what went where. But the truck side is not helping me figure out what to do.

Question 1. Isn't there supposed to be a pin that shows 12V only when the brakes are applied? I would assume this goes to the trailers brakes. There is not a pin on the truck that gets hot with brakes applied.

Question 2. Isn't there supposed to be a pin that shows 12V when the lights are turned on truck? I would assume this goes to the marker/running lights on the trailer. There is not a pin that gets hot when lights are applied.

Question 3. Why would the truck have 2 pins that show 12V at all times? All wiring diagrams I have read online only show 1 pin with a always hot 12V.

Note - left turn, right turn, and brake lights work

 

maybe this will help. if you have to use a batt to find what wire is what on the trailer.
no 12v on brakes would not work good. there is a 12v with the key on.
yse the 12v with lights is running lights
1 is the brake controller the other is the all time 12v.

 

Did you check the READ FIRST posts at the top of this FORUM??? There are wiring diagrams up there......http://www.ford-trucks.com/forums/59...0-13-10-a.html

 

Here is what is how the truck connector is behaving.

1. Ground - correct
2. Brakes - incorrect, always 12V. Shouldn't this only be when brakes are applied?
3. Markers - incorrect. Does not show 12V when the truck lights are turned on. Shouldn't this be 12V with truck lights?
4. 12V Aux - correct
5. turn/brake - correct
6. turn/brake - correct

Could a relay or fuse on the truck be causing these symptoms?

 

2. Your brake controller may be putting 12V on the plug to detect trailer brakes. Once it sees a circuit it would cut that power. What kind of brake controller do you have?

3. Check your trailer tow parking light fuse.

 

2 and 3 reversed?

 

Fixed it. Miswired trailer plug had blown fuse on truck effecting pin 3. Corrected trailer plugs 2, 3, and 1. Good to go now. Not a single wire color on trailer followed conventional color schemes. Nightmare.

 

Never-ever go by color codes when two different manufacturers are concerned....ALWAYS go by applied voltages!

BTW....CONGRATS on figuring it out! Persistence always wins out!