If the green LED is not lit, the DCC signal on the outer wires of the LocoNet cable is not reaching the DTM30. Check that:
- Track power is turned on;
- The LocoNet cable is not plugged into the fron connector of a UP3/UP5 type panel;
- All the LocoNet cabling is good.
Try connecting the DTM30 directly to the command station with a good LocoNet cable if all else fails, and work forward from there.