So just a thought after having my meth pump fail. The LED light that indicates you are spraying runs off the voltage sent from the controller to the pump, even if the pump was not there it would show you are spraying. My thought is to use an arduino board and a piezo sensor to show the pump is actually running. Better than that would be a flow meter to know something is coming out of the pump but I think this will do. This way we have a light to show the controller is on and a second light to show the pump is running. We can actually have any output you would like, maybe an alarm? Seems inexpensive and easy to build. It would be like any auto sensor with a 0-5v, the higher the voltage the more vibration. You can adjust the sensitivity in the code and I am hoping there will be a stark difference between the vibration of the pump from the car running and the vibration of the pump when it turns on making it easy to dial in the setting. Thoughts?
https://www.arduino.cc/en/Tutorial/Knock
