I had the same problem, I installed the jeep plug & play wiring harness, plugged it in to a test vehicle it worked fine. Plugged the 7 pin connector into the MH nothing, I had previously towed a utility trailer behind the MH with a 4 pin connector, using a 4 to 7 connector it worked fine. Then I found there was no power to the MH 7 pin connector, added a power line it all works fine now.