Knock Sensor: Description and Operation

Knock Sensor Cutaway View:

Knock Sensor:

PURPOSE
The knock sensor (KS) detects abnormal vibration (spark knocking) in the engine. The KS is mounted on the engine block near the cylinders. The KS is not actually part of the Distributor Ignition system; rather it is an input signal to the Engine Control Module (ECM) to allow the ECM to determine correct Ignition Control (IC) change of timing and timing advance.

OPERATION
The sensor produces an Alternating Current output voltage which increases as the amount of knock increases. This signal voltage is input to the ECM. The ECM then adjusts the ignition control to reduce spark knocking.

DIAGNOSTIC NOTES
Problems encountered with this circuit should set Diagnostic Trouble Code (DTC) 43.