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:
Park Brake and P (Park) Mechanism Check
Warning
When you are doing this check, the vehicle could begin to move. You or others
could be injured and property could be damaged. Make sure there is room in front
of the vehicle in case it begins to roll. Be ready to apply the regular brake at
once should the vehicle begin to move.
Park ...
Hood Primary Latch Release Cable Replacement
iv
Hood Primary Latch Release Cable Replacement
Callout
Component Name
Preliminary Procedures
Remove the radiator opening upper cover. Refer to Front Opening
Upper Cover Replacement.
Remove the air inlet grille. Refer to A ...
3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output Carrier
Installation
3-5-Reverse and 4-5-6 Clutch Housing, and Input, Reaction, and Output
Carrier Installation
Callout
Component Name
1
3? Reverse and 4?? Clutch Housing Thrust Bearing
2
2? Clutch Apply Plate ...
0.007