Tach and 4-in-1 Gauges not Working - Digital is Fine

[JeffH]

I can start both Cummins QSM-11's and I get a readout from my Cummins ED-4 C-Command digital gauges. But my tachs and 4-in-1's have no readout at all. Needles don't move. Any ideas??

Thanks, Jeff

 

[mikey18605]

Likely a bad MMDC, part not availible, can switch to analog gauges, but a lot of work/money.