Circuit Description

Knock Sensor (KS) system is used to detect engine detonation. ECM will retard spark timing based on signals from KS module. Knock sensors produce an AC voltage signal that is sent to KS module. Amount of AC voltage signal produced is proportional to amount of knock.

An operating engine produces a normal amount of engine mechanical vibration (noise). Knock sensors will produce an AC voltage signal from this noise. When an engine is operating, ECM will learn minimum and maximum frequency of noise the engine produces. When ECM determines that this frequency is less than or greater than expected amount, a knock sensor DTC will set.

Conditions required to set DTC are:

• Knock sensor signal is lower than values listed in KNOCK SENSOR SPECIFICATIONS table.