Voltage to knock sensor @ ~2.8V, bad ECM?
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From: Chicago, IL
Car: 2007 Volvo S60R, 2005 Audi A4
Engine: 300HP 2.5L I5, 200HP 2.0L I4
Transmission: TF-80SC, Getrag 6 speed
Axle/Gears: 3.33:1, 3.54:1
Voltage to knock sensor @ ~2.8V, bad ECM?
Checked the voltage at the knock sensor circuit with car off, ignition on. Measures around 2.8 volts, service manual says it should be 4-6V. Also, if I tap the block with a hammer like this, there is no change in voltage--shouldn't there be even though the car is not running (knock sensor is just a resistor variable w.r.t vibration right)? I've been getting a code 43.
Car is a stock 91 305TPI T/A.
TIA
Car is a stock 91 305TPI T/A.
TIA
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Joined: Jul 2003
Posts: 692
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From: Bellingham, WA
Car: 1989 RS
Engine: 3.1L + .060" overbore
Transmission: 700R4
Axle/Gears: 4.11, Auburn LSD
I don't think that you can measure the voltage difference with a voltmeter. The Knock sensor is a Piezo device, and reacts VERY fast. You will have to look at it with an o-scope. Try to disconnect the leads to the sensor. IF the sensor is bad, it may drag the ECM voltage down. Best I can do for you, good luck!!
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