Knock Sensor

The Knock Sensor (KS) is a piezoelectric device which detects abnormal engine vibrations (spark knock) in the engine. Engine is equipped with 2 knock sensors and are located on right side of engine block. See Figure . This vibration results in the production of a very low AC signal, which is sent from the KS to the KS module (integral to PCM). The PCM then retards ignition timing until the engine knock ceases.

A fault in the KS circuit may set a DTC. See SELF-DIAGNOSTICS - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.