Still getting "Check trailer wiring" message 2014 Silverado

Okay, I think I found the problem. Without the trailer attached to the ball hitch, I plugged the trailer cord into the truck. I was able to wiggle the wires and weird connectors just outside the trailer hub and recreated the problem. It must be a bad connection inside these weird connectors. Therefore, I'm going to replace all of these connectors. I'll try to post a pic of the weird connectors in a moment. What type of connection should I use?