Code P0328, Knock Sensor Open - "S" & "T" Series 4.3L (VIN Z): Notes

Knock sensor circuit consists of 2 knock sensors connected in parallel and a single wire to control module. Each knock sensor has a resistance value of about 8600 ohms. Control module supplies a 5 volt reference to sensors, but because of sensor resistance, it is cut to about 2.5 volts. When a knock occurs, a small AC voltage is generated by sensors on top of existing 2.5 volts. An AC voltage monitor in control module will detect this voltage and provide a signal to begin retarding spark until knock diminishes.

1. Control module applies 5 volts on sensor circuit which should be present at connectors when sensors are disconnected.
2. By verifying sensor resistance, problem can be narrowed to connector, sensor installation or control module.
3. Improperly installed sensor can prevent sensor from grounding to block.