Okay, Guys. Here is the issue.
I am having an issue with a couple G540's. These are on my mill. I was using G203V's up until about 6 months ago. I had a problem with that panel faulting in one axis and had all the stuff to build a new commercial type control box for them to run the mill in the future.
I had a 540 on hand and decided to use it for the time being until I had time to complete the new 203V box.

The G540 ran for 6 months with no trouble. A couple days ago, however, it started faulting out on me.
I was milling some text in steel like I normally do. It finished the first process and went to tool change position.
I changed the end mill and hit start. The computer dro's went, but no motion on the machine. The red led was lit on the G540.
I shut down the entire system and rebooted. When I hit the AC side switch to power up the drive system, I get a quick red led, then a variable time the green led lights, then into red.
I try it without the motors connected. Sometimes it works correctly, sometimes the same faulting. Tried it without the PP cable connected. Same intermittent fault. Sometimes the green led stays lit, sometimes not.
Done all the testing and switching to see that the enable switch and charge pump switch are working correctly. When they are off, it doesn't come out of red on startup.

I ordered another G540 to see if that was the issue. It wasn't.
It acted the same.
While I was waiting for the new one to arrive, I swapped out the PS, cables, and triple checked the wiring.
Same results.

Now the motors on the mill are 6A 1200 oz Nema 34's.
It has run those fine for 6 months, though I did have to reduce my acc. and Velo. in Mach some.

Removing the motors though still resulted in an intermittent fault at startup, so I don't think they are the issue. Checked all the motor cables as well and they are as they should be.

I am trying to finish up my G203V box ASAP now, but any ideas on the G540 faulting would be a great help down the road.
This will be needed with my Plasma cutter soon. I bought the full electronics package from CNC Router Parts.
The marking on the first G540 was I1. The second has H1.
Thanks a bunch.