How many of us are there? Owners of Dodge based RV's?

Maya,

OK, when it is hooked up the way it was originally, and the ignition on, and the display lit, use your voltmeter to determine which is terminal is positive and negative.

I say this because the way you are describing it sounds like the terminals are marked wrong, but this seem really unlikely. So, lets confirm with the volt meter.

Don't trust the color of the wires because we know these were not factory installed. They didn't have controller boards back when your RV was built.