2015 Jeep Grand Cherokee How to Install Trailer Wiring Harness. There is a wiring harness that has a 7 pin connector just under the rear bumper but when I connected the right adapter nothing works. Is there a connection under the hood that needs to be made

 

Is it a factory 7-pin connector? If so then everything should be hooked up. I'm sure there are many connections, not sure what all is under the hood. 7-pin connects running lights/ brake lights/ signals/ electric trailer brakes. Sometimes the 7-pin can be a tight fit, make sure it's plugged all the way in. You say "adaptor", is the trailer a 4-pin?

 

There was a cap at the end of the harness where you plug in the adapter for either a 4 wire or 7 wire. I purchased the 4/7 wire adapter from the dealership plugged it in but, it did not work. I asked the service guys about it and they said the was a fuse and or a connection that needed to be done.

 

I think you are clocking the adapter wrong, or it is not in all the way.

Are you certain that all your trailer lights worked before, with a different vehicle?

 

All I can tell you is my brother bought a Chevy Silverado all set up to tow his BIG house trailer and there was a wire in the harness under the hood that needed to be connected to power his trailer brakes. It was there, just needed to be pulled out of the cover and screwed to a power terminal close by.