Can anyone verify how a solid state glow plug controller (87 6.9) takes in temp input?

Is it the ambient temp of the controller itself, temp of coolant or both?

I am asking because I would like to simulate a 0 degree(Fahrenheit) cold start and ensure that the plugs stay on within spec.

Thanks!

 

well it is the temp of the electronics inside the controller from the haynes diesel supplement manual.

now to add confusion i have read the temp sensor has something to do with it, but what i cannot tell as they are not connected in any way in any wiring diagram i have seen.

so to do this you will have to cause the controller to become frozen.

 

I also have wondered this. My glow plugs always cycle for 10-15 seconds no matter what engine temp. My oe temp gauge always reads cold and like you, all the wiring diagrams I look at they are not tied together. I have tried I think 3 different controllers and same results. Just bothers me a little haha