At 42 degrees F you are right at the threshhold for the Relion batteries to go to heat mode first, then charge etc. When that happens, there can be delays in the ability of the generator to work as expected. At least that is what happened to mine.
There has been some speculation that when this happens, the batteries will not allow power to run through the inverter as you would expect. If you can try this perhaps tomorrow when temperatures are a little higher, you will have your answer. This is the data directly from the Relion battery data sheet:
HEATING ELEMENT SPECIFICATIONS
Heating Temperature Range -4 to 41 ºF (-20 to 5 ºC)
Heating time- Approximately 1 hr @ 10 A
The other thing you should probably confirm is if your Balmar display is lit up and working normally ( showing voltage). If not, you can try and hold down the button near the drivers seat for 5 seconds to connect the two battery banks (coach and chassis). It is labeled "emergency start". If that corrects the problem, your Balmar display will light up and show voltage. Thor's explanation for this is that the procedure will "wake up" your batteries.
Then try and reconnect the generator.
I am assuming with these instructions you are in a Tellaro or Sequence with the Promaster configuration as well as Relion batteries.
There is a video of this procedure posted by another user at:
https://www.thorforums.com/forums/f4...old-33225.html
Good Luck!