Chevrolet Sonic Repair Manual: Knock Sensor System Description
- Circuit/System Description
-
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
-
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:
If No Steam Is Coming from the Engine Compartment
If an engine overheat warning is displayed but no steam can be seen or heard,
the problem may not be too serious. Sometimes the engine can get a little too hot
when the vehicle:
Climbs a long hill on a hot day.
Stops after high-speed driving.
Idles for long periods in traffic.
If the ...
Wheel Alignment and Tire Balance
The tires and wheels were aligned and balanced at the factory to provide the
longest tire life and best overall performance. Adjustments to wheel alignment and
tire balancing are not necessary on a regular basis. Consider an alignment check
if there is unusual tire wear or the vehicle is signi ...
Side Window Defogger Outlet Grille Replacement
Side Window Defogger Outlet Grille Replacement
Callout
Component Name
1
Side Window Defroster Outlet Grille (Qty:?€‰2)
Procedure
Use a flat bladed plastic trim tool to aid in the removal of the grille
ass ...
0.0058