I'd like to install a switch to manually keep the grid heater on, rather than having it cycle back and forth. Anyone know how to do this?

I'm guessing it operates based on the temperature inside the intake manifold? Or perhaps the surface temp of the grid heater itself?

 

Easiest way is to simply run a push button to ground, then to the ground side of the solenoid control. Power is always applied to the solenoid, black with green stripes. The ground is the black with tan/yellow and black with orange. I used ring terminals on mine when the connectors were corroded and 10-32 nuts.

 

Too much amperage for leaving it on for an extended period.