Knock Sensor: Description and Operation

Knock Sensor Circuit:

Purpose
The Knock Sensor sends a signal to the Powertrain Control Module (PCM) to retard ignition timing during a spark knock condition. When engine detonation stops and there is no knock signal being sent to the PCM, timing is advanced in small increments. This allows the PCM to maintain maximum timing advance under various engine load conditions.

Operation
When abnormal engine vibrations (spark knock) are present, the sensors produce a voltage signal. These signals are received by the PCM via the Knock Sensor Module. The PCM fluxuates ignition timing to maximize performance and minimize spark knock.