Around the water pump and thermostat housing on the 1ggte there is the green plug water temp sensor which obviously goes back to the ecu. What I want to know is what is the brown plug next to it?

The reason I'm asking this question is because im running a LT8 microtech, and the only Aux output on the ecu is being used for the thermo fans. I would like to use it to use the AUX output instead to activate TVIS. Ideally I want to run my thermo's off a thermostat switch, to free up that AUX output. If this brown plug isnt a thermo switch, can someone suggest a way in which they have run a thermoswitch?

Your thoughts and help is appreciated