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
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Other materials:
Heated Front Seats
Warning
If you cannot feel temperature change or pain to the skin, the seat heater
may cause burns. To reduce the risk of burns, people with such a condition should
use care when using the seat heater, especially for long periods of time. Do not
place anything on the seat that insulates again ...
Tires
Every new GM vehicle has high-quality tires made by a leading tire manufacturer.
See the warranty manual for information regarding the tire warranty and where to
get service. For additional information refer to the tire manufacturer.
Warning
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Fluid Cooler Inlet Hose Replacement
Removal Procedure
Remove the battery tray. Refer to
Battery Tray Replacement
Remove the front bumper fascia opening lower cover.
Refer to Front Bumper Fascia Opening Lower Cover
Replacement
Remove the front wheelhouse liner inner front extension.
Refer to Front Wh ...
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