I'm back. Sorry about letting the tread go cold, but we got busy in the field. If I have new eyes and brains here, the old thread is here: Combine grain loss sensor questions | All About Circuits . We used the combine to cut rye, and I managed to catch (as a couple people mentioned) that I had lost continuity in the shielded signal wires. They were showing somewhere between 20 and 50 ohms. I'm guessing that's not good for a signal wire, so I luckily happened to have some shielded cable on hand and replaced it all the way into the cab. I would guess there may have been some corrosion, but that did not fix our problem. So, we know we have 8V and a good ground to the sensors and a new shielded cable running to them. If we can't find a problem with the sensors, the problem could be the module in the cab which I was told by a mechanic was very uncommon (as in he had never seen it). I bought an oscilloscope and power supply as suggested, and an attempt was made at taking some measurements. With 8V applied to the circuit, the voltage between R1 and R5/T1 (sorry if my labelling is confusing) was 1.8-2V. From R5 to R4 voltage was 600mV. After C1/T1 I could not get any voltage reading. Tapping the piezo I could not get any response anywhere in the circuit with 8V applied. It's very possible I do not have the scope set correctly to catch the signal (first time I've used one). However, with the power supply disconnected and the scope probe ungrounded I was able to get a 60 Hz signal when tapping the piezo (also showed negative 1.6-2V but does that mean anything if measuring from a single point?). Again, I am not an electrical engineer; I am a farmer who greatly appreciates your help. I was flattered by the response I received on my last post. You should be proud of your community. Thank you again, Robert.