Chevrolet Sonic Repair Manual: Knock Sensor System Description
- Circuit/System Description
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The knock sensor system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The ECM uses the knock sensor system to test for abnormal engine noise that may indicate detonation, also known as spark knock.
- Sensor Description
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This knock sensor system uses one or two flat response dual-wire sensors. The sensor uses piezo-electric crystal technology that produces an alternating current (AC) voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency are dependant upon the level of knock that the knock sensor detects. The ECM receives the knock sensor signal through 2 isolated signal circuits.
If the ECM has determined that knock is present, it will retard the ignition timing to attempt to reduce the knock. The ECM is capable of controlling spark retard on an individual cylinder basis. The ECM will always try to work back to a zero compensation level, or no spark retard. knock sensor diagnostics are calibrated to detect faults with the knock sensor circuitry inside the ECM, the knock sensor wiring, or the knock sensor voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive mechanical engine noise.
Knock Sensor Replacement
Knock Sensor Replacement
Callout
Component Name
Preliminary Procedures
Disconnect battery negative cable. Refer to
Battery Nega ...
Heated Oxygen Sensor Replacement - Sensor 1
Heated Oxygen Sensor Replacement - Sensor 1
Callout
Component Name
Warning: In order to avoid being burned, do not service the ...
Other materials:
Power Windows
Warning
Leaving children in a vehicle with the keys is dangerous for many reasons.
Children or others could be badly injured or even killed. They could operate the
power windows or other controls or even make the vehicle move. The windows will
function and they could be seriously injured or k ...
Brake Pedal Position Sensor Calibration
Calibration Criteria
Note: Do not apply the brake pedal during the brake pedal position
sensor calibration procedure. Any movement of the brake pedal during this
procedure will cause the calibration procedure to fail. If this occurs,
the brake pedal position sensor calibrati ...
Replacing Engine Gaskets
Gasket Reuse and Applying Sealants
Do not reuse any gasket unless specified.
Gaskets that can be reused will be identified in the service procedure.
Do not apply sealant to any gasket or sealing surface unless called
out in the service information.
Separating ...
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