K 3500 Truck 4WD V8-454 7.4L (1994)
Knock Sensor: Description and Operation
Purpose:
The Knock Sensor (KS) is used to detect engine detonation (ping).
Operation
A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to
about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on
top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start
retarding the spark incrementally.
