When I connect my 75/10 to the battery terminals and the solar panel, it charges the battery. But, after I disconnect the solar panel from the mppt controller, the 12v system is dead. If I remove the 75/10 controller from the battery terminals completely, then the 12v system works fine again.
I am not using the "load" terminals and they are disabled in the bluetooth app. I have not modified the wiring to the converter installed in the trailer. All I did was attach the leads from the mppt controller to the battery and then attach the solar panel to the mppt controler. All of the fuses are good and the trailer wiring works fine as long as the mppt controler is uninstalled.
I am at a loss about my next step.