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:
Vehicle Identification Number (VIN)
This legal identifier is in the front corner of the instrument panel, on the
left side of the vehicle. It can be seen through the windshield from outside. The
VIN also appears on the Vehicle Certification and Service Parts labels and certificates
of title and registration.
Engine Identifi ...
Fog Lamp Aiming
Preparation Procedure
Note: Horizontal aim is not adjustable on this vehicle. Vertical
aim is done by an adjusting nut located on the rear of the fog lamp. Prior
to aiming the fog lamps, perform the following steps:
Completely assemble all of the components on the vehi ...
Exhaust Rear Muffler Replacement (LUV,LUW)
Special Tools
CH-6614 Chain Pipe Cutter
For equivalent regional tools, refer to Special Tools.
Removal Procedure
Warning: Refer to Exhaust Service Warning.
Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
Cut the exhaust rear mu ...
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