Jim I see you got a range of readings on G, M & Q. I have just been powereing up the two panels I have here with similar strange results for those ones when using a digital meter.
I don't have a 90A installation, I was just powering them from the main chokes, so I have no voltage coming through the charge warning light supply. Yet that point = G was giving various readings!
M is straight through connection, but has no connections to it either end of it after it leaves the box.
Q is the supply for the battery relay that comes as an independant output from the generator. That was neither revolving nor plugged in, yet it was giving readings!
None of those gave a steady ready of anything even with the prods not touching anything there is this annoying 'hunting' by the meter giving a gibberish display. Connecting it to those points there was a little bit more consistency but still nothing at all stable. I was still getting these readings with no power to the panel!
Putting on, what I call a proper meter, an Avo 7 there was no reading at all, which as one would expect. So unless the digital display remains stable it is just gabbling away to itself. I think the reason that it became marginally more stable was that it was charging up a bypass capacitor that is present in the wiring of each of those test points.
I would have thought in this day & age it might be conceivable to develop a meter that only displayed a reading when there was something there to read, rather than make meaningless random displays with the meter prods not touching anything. So I have dusted down my Avo 7 & going to do the same to my Avo Multiminor & that isn't quite so heavy to carry in a vehicle.