Circuit Description

The Knock Sensor (KS) is used to detect engine detonation. ECM will retard ignition timing based on signals from KS module. KS sensors produce an AC voltage signal that is proportional to amount of vibration engine is experiencing. ECM records a fault when engine noise falls to less than a certain threshold (based on engine load and speed). DTC will set after 20 faults have been recorded.

DTC will set if fault KS system and the following conditions are met:

• ECM has learned a minimum noise level at idle for 5 seconds and does not detect a change in noise level between 2500-3500 RPM for 5 seconds.
• ECT greater than 104°F (40°C).
• Engine run time is greater than 10 seconds.
• Engine speed greater than 2000 RPM.
• No ECM internal failure DTCs are set.