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.
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?
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.