Knock Sensor tests - 90 Camry V6

I’ve got a 90 Camry with the 2.5L V6, showing a Check Engine code of 52, Loss of Knock Sensor Signal. I tried cleaning up the contacts, but still get the Signal Loss code. Are there any tests to determine whether the knock sensor is bad? Or should I go use the process of elimination to first rule out the wiring by establishing continuity to the ECM, and then assuming it must be a bad sensor? What causes them to go bad?

(The knock sensor came on after the car was sitting for a week while I replaced the right side tie rod end, the right side lower control arm, both half-axles, the rotors and pads, and the power steering pump hose. Because there was congealed grime from leaky power steering fluid everywhere, I was more than a little liberal with the Gunk Engine Degreaser.)

(Okay, it was more like three weeks.)

Or is what I’m looking at NOT the knock sensor? It’s SOME kind of sensor, right next to the #1 injector connector. The wire disappears into the main intake manifold wiring harness.

A Chilton book has one diagram covering both the 2.5-liter and the 3-liter V-6’s: the diagram shows 2 knock sensors, located roughly by the #3 and #4 cylinders. My 1990 Toyota Camry book (volume 2) shows only one knock sensor, but I’m looking at the electrical circuit diagrams, not a component locator view of the engine management system, which would be in volume 1. Which I don’t have. Yet.

A timing light can be used to determine if the knock sensor is functioning. Connect the timing light, and with the engine idling, tap on the engine with a wrench near the knock sensor. If the knock sensor is functioning, you’ll see the timing marks change with the timing light.