Originally Posted by Daubsy
Im stumped. I used jumper wires to connect the controller directly to the pigtail, and it still didn't work. Voltage from the pigtail is reading 12.7 - 13.4v, so the controller should be powering on. Im using this controller
It must be in the way that the 7-pin trailer cable is wired to the battery?
Let me see if I can help, by saying it in my words:
First, here is a diagram that is very clear, and has both color schemes used for trailers (traditional, and RV).
Trailer Wiring Diagrams | etrailer.com
Scroll down until you find the 7 pin pics. Ignore the one on the right. traditional and RV only differ in some of the colors used; the pin outs are the same.
12V+ is on the top, off-center to one side, and ground is on the bottom on the other side, directly across the circle.
Pin 4 is black (12V+)
Pin 1 is white (Ground)
To verify the 12V+ pin, you can take the ground (black) probe on your meter and find a bare metal spot or bolt on your trailer frame to connect it to. If you find a spot or bolt for the ground probe, then poke around with the hot probe (red) in your plug until you get a 12V+ reading on a pin.
Now re-test with the red probe still on that pin, and the ground probe on the pin on the opposite bottom pin. That should give you the identity of your pins.
Or, you can test pairs of pins, working your way around the circle, and always with one probe 180° opposite the other probe.
Help this helps; remembering that electrical troubleshooting is a misnomer, it's really lots of fun.