Q: Why does my M3491/INN3491 light both arrows?

A: This normally happens when the two black wires from the unit are connected together.

1. This unit constantly maintains +24vdc to the RED and GRN wires, and when the appropriate arrival signal is received, it connects the corresponding BLK wire to GND.  If you only have one common wire for your lantern, then connect the RED and GRN wires together to the lantern common, then connect the BLK wire that was paired with the GRN wire to the UP lantern and the BLK wire that was paired with the RED wire to the DOWN lantern.