How do knock sensors work / how to test?
 

Have knock sensors on the boat I am buying. In the sea trial, I never saw one move. That might be a good thing, if they are working. How can you / do you test them? These are Gafrig gages.

Re: How do knock sensors work / how to test?
 

Knock sensors are a piezo electric crystal signal generator. The vibration, at the correct frequency causes the crystal ti vibrate and generate a small electrical signal. this signal then shows on the scan tool or dash readout after being modified by the computers electronics. Test by tapping the bolck with a small hammer near the sensor.

Re: How do knock sensors work / how to test?
 

Thanks!