Any an all advice is appreciated!

[Nasty-Z]

Or simply parallel relays to provide a fail safe ......

I like the idea of a fan in operation light , I have two in the switch panel in my Blazer , one for each fan. Only thing they will not tell you is if the motor craps the bed , that is what the Water temp Pro lite is for .

As for the trans , are you sure there is a definite 1-2 shift ? Only reason I ask is default gears on a 4L80E is second and reverse with no operation of the shift solenoids , meaning no power (+12v) to the trans , or no communication with the PCM and the trans.

TOM