Knock Sensor: Description and Operation
DESCRIPTIONTo control spark knock, a Knock Sensor (KS) system has been added. This system is designed to retard spark timing up to 20', to reduce spark knock in the engine. This allows the engine to use maximum spark advance to improve driveability and fuel economy.
Varying octane levels in gasoline can cause detonation in engines. Detonation is called spark knock.
OPERATION
The KS system has two major components:
^ KS Module
^ KS System
The sensor is mounted in the engine block under the Intake Manifold assembly. When the KS detects abnormal vibration (spark knocking) in the engine, it produced a voltage that is received by the KS module. As long as the KS module sees no voltage from the KS (knock not present), it sends a signal voltage (8 to 10 volts) to the Engine Control Module (ECM) and the ECM provides normal spark advance.
When the module detects voltage from the KS (knock present), it turns "OFF" the signal to the ECM and the voltage at terminal "D10" goes to 0 volts. The ECM then retards ignition control (IC) to reduce spark knock.
The KS signal line has a shield wire to prevent any false signals to the KS module. If the shield wire loses it ground a false diagnostic trouble code (DTC) 43 may result or the ignition timing maybe retard needlessly.