I had a Trane YCH unit where nothing was running. Power was on, fuses OK, no obvious problems. Following the instructions in the Voyager Microcontrols manual, I checked the UCP LED (it was on), then checked LTB terminals 6-9. There was OvDC, so I installed a new UCP and the unit started.
Being curious, I checked LTB 6-9 again, and the voltage is still 0. Normal should be 32vDC.
Am I doing something wrong, or is there still a problem with the unit?