I have an issue witht the lights on my 2002 Flafstaff PU. The lights do not work on the battery but do work when pluged into SP. New battery, new converter and still no lights. I have 12V coming from the battery to the converter. I've checked the grounds and all look good. No blown fuses. I checked the continuity of all the fuses, replaced all fuses, and nothing 12V works off the battery. Measured the voltage from the 12V lead from the battery at the converter. (13.6V)What next?