Stupid knock sensor question
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Le Mans Master
Joined: Feb 2002
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Stupid knock sensor question
How do they technically function?
Do they generate a voltage signal only upon sensing knock, or do they provide a constant voltage signal all the time that is pulsed or fluctuated when they sense knock, i.e. knock event causes resistance that lowers the voltage?
Do they generate a voltage signal only upon sensing knock, or do they provide a constant voltage signal all the time that is pulsed or fluctuated when they sense knock, i.e. knock event causes resistance that lowers the voltage?
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Joined: Dec 2000
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From: SE NY
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The later C4s used a direct connection between knock sensor and ECM (earlier had an ESC unit).
Here the ECM supplies a constant voltage (~6Vdc) on the line to the knock sensor; when knock occurs the sensor modulates an AC signal onto that DC voltage.
Here the ECM supplies a constant voltage (~6Vdc) on the line to the knock sensor; when knock occurs the sensor modulates an AC signal onto that DC voltage.
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Originally Posted by 65Z01
The later C4s used a direct connection between knock sensor and ECM (earlier had an ESC unit).
Here the ECM supplies a constant voltage (~6Vdc) on the line to the knock sensor; when knock occurs the sensor modulates an AC signal onto that DC voltage.
Here the ECM supplies a constant voltage (~6Vdc) on the line to the knock sensor; when knock occurs the sensor modulates an AC signal onto that DC voltage.
