00:00Hi everyone just a quick video on knock sensors what they are and what they do so I've got one
00:05here from a customers car I'm just going to test it in a moment so what is it well it's a sensor
00:10an active sensor that picks up vibrations from the cylinder and controls the ignition timing so
00:16location wise normally find them on the side of the engine block so hopefully you can see that
00:21little blue sensor down there or the one with the blue dot on it that's the knock sensor on
00:26the side of engine block and as it sits there it picks up the vibrations from the cylinder if the
00:32spark plug goes off too early it will hit the piston as a piston still traveling up rather than hitting
00:36it square in the face at top dead center so it can drive the piston down so the knock sensor is the
00:42main sensor for controlling when the spark plug fires for engine timing so how are we going to test it so
00:47normally it'll be a 0 to 5 volt sensor the easiest way to test them though is to get your multimeter
00:53and set it to the lowest setting which is 200 millivolts um I'm going to simulate the knocking
01:00by actually tapping this uh knock sensor and hopefully I'll get some sort of voltage out of it
01:05but obviously the voltage I get will be a lot lower than it would actually be uh when the engine's
01:10vibrating so I'll set you guys here I've got my multimeter there and I've got two crocodile clips
01:17so I'm simply going to put onto this uh these two terminals here so on that and
01:26a bit of a tight fit there we go so what I'm going to do now is get my knock sensor
01:36and knock it on the bench and hopefully I should get some sort of voltage out of it
01:40as you can see it is producing a small amount of voltage and that small amount of voltage tells
01:58me that the wiring inside there is okay and the sensor itself is working so a quick way to test an
02:02knock sensor um and I hope that makes sense and we'll uh we'll see you in the next one
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