The d+ status is ONLY if they connected to Ignition side of the chassis engine to auto lock the refer doors when the ignition is ON. Nothing else it does. Follow the 120 element wires (you have 2 elements connected together) to the control board. With the refer on Electric (auto), measure between the 2 spade terminals AT the control board for 120. The odds are you will NOT have 120 power there. Then check the fuse for the 120 on the board. IF you do have 120 at the Heater connections, then the elements are bad. Doug