Lot's of good responses
You could very well have a wiring issue! This system is pretty straight forward.
*Unplug the Knock Sensor jumper harness, With the key-on engine off, Probe the engine harness side, You should have a 5vdc bias voltage on BOTH knock sensor circuits, It can be slightly lower than 5 volts.....Like 4.95vdc for example.
*Both Knock Sensors should "ohm" at @ 99,000 ohms, Taken at the Knock Sensor jumper side.
*The 99,000 ohm bleed resistor will knock down the 5vdc bias voltage @ 1/10th of a volt or 100mV when reconnected. I recommend "backprobing" at the PCM connecter with a T-pin.
*These 2 circuits are very sensitive....You may want to disconnect both PCM connectors (7mm socket), Blow them out good & reconnect them!!
*More in depth diagnosis will require a scope so you can watch the AC sine wave that rides the 5vdc bias voltage when noise is introduced via knocking on the block.