First, I found this phone number on the Coleman website - 1-800-835-3278.
Perhaps, they can help you find the wiring diagrams for your trailer. Have the model number ready.
Second, since all the lights are out, and you've occasionally seen a glow, I'd suspect a bad ground. One of your pins on the connector is connected to ground. Try connecting that pin directly to ground and see if that brings on the lights. If that works, eastablish a new ground for the connector.
W8RLM - Bob
2006 Winnebago Journey, Model 39K, 2013 Dodge Dart