K 2500 Truck 4WD V6-262 4.3L VIN Z TBI (1995)
Knock Sensor: Description and Operation
Knock Sensor
PURPOSE:
The knock sensor's signal retards ignition timing during a spark knock condition to allow the control module to maintain maximum timing advance
under most conditions.
OPERATION
A 5 volt reference is applied to the knock sensors which has an internal resistance of about 8200 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.
A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM
applications. On PCM application no KS module will be found as it is internal to the control module.
