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:
Tire Rotation
Tires should be rotated every 12 000 km (7,500 mi). See Maintenance Schedule.
Tires are rotated to achieve a uniform wear for all tires. The first rotation
is the most important.
Anytime unusual wear is noticed, rotate the tires as soon as possible, check
for proper tire inflation pressure, an ...
Airbag Front Passenger Presence Sensor Replacement
Airbag Front Passenger Presence Sensor Replacement
Callout
Component Name
Warning: Replace the passenger presence system as a complete
assembly to prevent possible injury to the occupant. All the components
in the se ...
Brake Pedal Pushrod Inspection
Disconnect the brake pedal pushrod (2) from the brake pedal.
Reposition the pedal pushrod boot (1) toward the front of the vehicle to
expose as much of the pedal pushrod (2) as possible.
Inspect the brake pedal pushrod (2) for straightness.
If the brake p ...
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