The fact that you see that message on your EFIS-D10A implies that it was connected at some point, but it's not right now. If you'd never had it connected, the EFIS-D10A would be using its internal magnetic sensors.
So, the first thing to check is the continuity of the 4 wires that connect the EDC-D10A and and the EFIS. Make sure the pins are continuous, and that they are "clicked" into place in the connectors on each end.
