System Description

The Knock Sensor (KS) system is used to detect engine detonation, allowing the Engine Control Module (ECM) to retard the ignition control spark timing based on the KS signal being received. The KS produces an AC signal so that under a no-knock condition the signal on the KS circuit measures about 0.007 V AC. The KS signal's amplitude and frequency depend upon the amount of knock being experienced. The ECM contains a non replaceable knock filter module called a Digitally Controlled Signal-to-Noise Enhancement Filter (DSNEF) module. This filter module in the ECM determines whether or not knock is occurring by comparing the signal level on the KS circuit with the voltage level on the noise channel. The noise channel allows the ECM to reject any false knock signal by knowing the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load. When the ECM determines that an abnormally low noise channel voltage level is being experienced, Diagnostic Trouble Code (DTC) P0324 will set.