The Knock Sensor (KS) is a piezo-electric (pressure-sensitive) electronic device that enables the Powertrain Control Module (PSM) to control the ignition timing for optimum performance, and to protect the engine from potentially damaging levels of detonation. The PCM uses the KS system to test for abnormal engine noise that may indicate detonation, which is also known as spark knock.
Removal & Installation
Before servicing the vehicle, refer to the Precautions Section.
NOTEDisconnecting the negative battery cable on some vehicles may interfere with the functions of the on-board computer systems and may require the computer to undergo a relearning process, once the negative battery cable is reconnected.
NOTEIf working near and/or around the SRS system and components, be sure to properly disable the SRS system. See disarming/arming the SRS system.
- Disconnect the negative battery cable.
- Raise and safely support the vehicle.
- Disconnect the electrical connector.
Remove the sensor from its mounting.
- Installation is the reverse of the removal procedure.
- Using the GM diagnostic scan tool or aftermarket equivalent reprogram the necessary systems and components. Be sure to follow the scan tool manufacturer-s directions.
Knock Sensor Strategy
The Knock Sensor (KS) system uses one or two broadband one-wire sensors. The Knock Sensor generates an AC voltage signal of varying amplitude and frequency based on the engine vibration. The amplitude and frequency are dependent upon the level of knock that the KS detects. The control module receives the KS signal through a signal circuit, and the KS ground is supplied by the engine block through the sensor housing.