2013 Transmission / Engine Temperature Issues, possible wiring problem? Something else?

[RadoRevival]

I have a 2013 Silverado every now and then my transmission temp goes crazy. Right after startup it goes up and down with temp warning when it is obviously not an accurate reading. 

 

Also, a couple times I got the engine too hot AC off warning. The thermostat will be stuck at 0 with this warning. When I pull over, plug in my code reader and clear the P0128 code, the thermostat goes to normal temp and the warning goes away. 

 

Could these be related? Hard to believe I have BOTH these issues. But I guess its possible. Any clues how to hunt this down?

[richard wysong]

You will need a scan tool that does live data so that you can see the temp outputs to the PCM to begin the diagnosis.