Knock Sensor Wiring - 2wire or 1 wire??

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Oleschool
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Knock Sensor Wiring - 2wire or 1 wire??

Postby Oleschool » Mon Jun 30, 2014 11:50 am

I just bought a knock sensor off of Ebay and when I received it only one wire from the harness was connected.There are two connections on the plug and on the sensor but only one wire was connected.Shouldn't both wires be hooked up?I connected the second wire and cleared the code.

Can someone chime in and let me know if I'm on the right track?This is for a 97 Pathfinder.


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smj999smj
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Postby smj999smj » Mon Jun 30, 2014 1:07 pm

Knock sensors, much like O2 sensors, use precious metal which generate a small voltage which the ECM reads. There are technically two wires in the circuit, but only one, a white wire, between the ECM and the knock sensor. The other circuit is a wire that runs from chassis ground to the shielded insulation around that wire wire.

Oleschool
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Postby Oleschool » Mon Jun 30, 2014 8:19 pm

I tried to confirm the continuity between the housing of the knock sensor and one of the wires and there was none.I removed the wiring connector and connected the wire which was cut off inside the connector.I reconnected the wire that connects to the shielded part of the harness for the original wiring. I've connected it and am driving the truck but want to make sure that it is the correct.I contacted the vendor who sold it to me and they said that it was only supposed to have one wire connected.What is right here?

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smj999smj
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Postby smj999smj » Tue Jul 01, 2014 5:57 pm

There is only one wire to the sensor, which is the white wire to terminal 2 of the knock sensor harness connector; the terminal 1 should not be connected to anything. The shield that insulates the wire has it's own wire that goes directly to body ground through a joint connector. There should be no continuity between the sensor and white wire. As I mentioned, the sensor "generates" a voltage signal which is read by the ECM.


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