I am installing a Progressive Dynamics PD4045 to replace the 25 year old Centurion CS3000 in my 1999 Jayco popup, and I have a question. The AC side of things is working, all of the outlets are as they should be, but I can't get the 12VDC to work. Since there are no installation instructions as far as how to use the black wires coming from the back of the converter, I assumed that the black wire coming out of the back of the converter should be connected to the black wire from a 12VDC light...