Knock Sensor: Description and Operation

Knock Sensor (KS):

Knock Sensor Circuit Diagram:

PURPOSE
Varying octane levels in today's gasoline can cause detonation in high performance engines. Detonation is sometimes called spark knock.

To control spark knock a Knock Sensor (KS) system is used. This system is designed to retard spark timing up to 10° to reduce spark knock in the engine. This allows the engine to use maximum spark advance to improve driveability and fuel economy


OPERATION
The KS system has two major components:

^ KS module (located in the Powertrain control Module (PCM).

^ Check KS.

The KS detects abnormal vibration (spark knocking) in the engine. The sensor is mounted in the engine block near the cylinders. The sensor produces an A/C output voltage which increases with the severity of the knock. This signal voltage inputs to the PCM. The PCM then adjusts the Ignition Control (IC) timing to reduce spark knocking.