The first thing I would do is get your Multi Meter out and check the output of each pin on your truck connector. There should be markings on the cover that tell you what pin does what.
Be sure you have someone operate the brakes of the truck when you test that pin.
If you get no power when you should have it at any pin go to your owners manual and look for the fuse, usually under the hood on the Dodge, that controls that function.
Make sure that the connector is plugged in properly you can get those connectors in at an odd angle even though they are keyed and they wont fully engage.
Check your wiring under the trailer there may be an inline fuse somewhere that is blown.