Taz 5 resets after pre-heating bed unless I start printing

I’ve been having a bit of an odd issue for some time. Often during bed pre-heating my board will reset and i’ll have to connect again and start pre-heating again. To be clear, this is almost always if i connect and start to heat the board with a manual command through Simplify 3D it will reset regardless of how I started the heating. However, when I start a print with all gcode temp settings, it almost always will make it through the heating and will start printing in fact I don’t recall it resetting when I start. Once it’s printing, it has never reset one time during a print. So it’s as if when I set it to pre-heat not as part of a full print, it has some issue and will reset randomly. The reset is always after the bed is over half-way to the target temp or even after it gets to target temp and is just holding there.

The strangest part of the behavior is that it never happens if I go ahead and start the print. Once the head is moving, the bed stays right at the correct temp.

This has been going on for 2 years over the course of 100’s of prints so it’s a fairly consistent pattern. I will say that i have loaded different firmware versions over this time to see if it ever had a change in behavior. The most notable change is how/when the board fan comes on during the pre-heat phase. The most recent firmware causes the case fan to come on full speed almost immediately after the board heating begins. On previous firmwares the board fan would ramp up and to my recollection was rarely at 100%.

Any ideas? I don’t think there’s a short in any of the heat bed wiring as i’ve moved some cables while it’s pre-heating and can’t cause it to reset that way.