Circuit Description

The DTC P0328 Knock Sensor (KS) Circuit High Frequency diagnostic monitors the activity on the KS circuit. The KS is non-resonant design that is constructed of a piezoelectric element which generates an AC signal when vibrated. Normal engine operation will cause the KS to generate signals of known frequencies. When engine knock is present, the KS frequency changes. This signals the powertrain control module (PCM) to retard ignition timing. The PCM sends a bias voltage of 5 volts to the KS on the KS signal high circuit. The PCM expects approximately 2.5 volts back on the KS signal low circuit. The KS generated AC signal rides on top of the bias voltage provided by the PCM. For additional information on the operation of the KS, refer to Knock Sensor (KS) System Description .