Having problems with a newly installed OEM Wire Harness

Everything is hooked up correctly, but it isn't working. There is appx 12v (I believe volts) going to all 'ports' on the harness...but It isn't transferring to a trailer? also, when I press the brake or turn indicator lights on, there is no change in the Volts. There is also current going to the harness when the outlander is off.

Does the mits. computer need to be told there is a trailer wire harness installed?

 

I had this problem. The grounding is awful for the electronics box you mount above the wheel well. I had to scratch off the paint and check the ground before attaching the ground wire.