Knock Sensor: Description and Operation

PURPOSE
Provides a signal to the ECM when engine detonation occurs.

LOCATION
Knock sensor is mounted in engine block under the L.H. exhaust manifold. The solid state module is near the upper R.H. corner of the inner fender.

OPERATION
When abnormal engine vibrations (spark knock) are present, sensor produces voltage signal which is received by knock sensor (KS) module. As long as KS module sees no voltage from knock sensor, KS sends a signal voltage (8 to 10 volts) to ECM which in turn provides normal spark advance. When the sensor detects a knock is generates voltage. When the KS module receives this voltage it reduce the signal to the ECM to O volts. The ECM then retards the ignition timing.