Knock Sensor: Description and Operation

PURPOSE:
The Knock Sensor (KS) is used to detect engine detonation (ping). The control module will retard the electronic spark timing up to 8° based on the signal received.

CONSTRUCTION
The KS system has two major components:
- Control Module.
- Knock Sensor(s). The two knock sensors are spliced together and go directly to the control module.

OPERATION
The knock sensor internal circuit causes the control modules 5 volts to be pulled down to about 2.5 volts. The knock sensor produces an A/C signal which rides on the 2.5 volts DC signal. The AC voltage monitor in the control module will detect this AC voltage and provide a signal to begin retarding spark until the knock diminishes. The amplitude and frequency are dependent upon the knock level.

LOCATION
Engine block.