Note. For circuit reference, see WIRING DIAGRAMS article.
Circuit Description
Knock Sensor (KS) is used to detect engine detonation. The KS is a piezoelectric element which generates an AC signal when vibrated. Normal engine operation will cause KS to generate a signal of a certain known frequency. When engine knock is present, KS frequency changes which signals the PCM to retard ignition timing. By retarding ignition timing, engine detonation detected should be reduced.