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1994 S10 Blazer 4.3 2 knock sensors 1 driver side between spark plug 3 and 5 second knock sensor location is passenger side rear engine below distributor. They are connected together and a single wire goes to B15.
I have a code 43. I cannot get the code cleared.
I have 5 volt reference at both sensors. When I ping the sensors they produce ac voltage.
My first question is,
Because the two sensors are wired together why do I need both connected?
Second question is if 5 volt reference becomes grounded does that fry the ECM?
Anybody any help would be greatly appreciated failed emissions test obviously and I'm suckin gas like an old 427.
Both sensors have to be connected as the pcm monitors both sensors using a single signal wire. You can by pass but not by disconnecting one.
The signal is not being grounded... the knock sensor produces voltage from the sound it hears much like a microphone.
The pcm goes into limp mode and adds fuel when the knock error is detected. Check your fuel trims, most likely your engine is running lean causing a lean misfire. This will set off the knock sensor.
The sensor is reporting a condition which may not be the failure of the sensor.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Okay, thank you that was helpful.
How does a 5 volt reference signal receive feed back.
Each sensor has a small resistor which is connected to ground this resistor normally provides some feedback to the computer so does the computer add the two resistor feedbacks to obtain a normal reading. I'm just not understanding how is single wire monitors two separate appliances.
So here's what I'm thinking. As an example 1 resistor provides a 250 ml reference which the computer picks up but because the other sensor is not connected it does not pick up the second 250 ml vote signal and therefore sees that as an error am I right in thinking this way.
I believe the technology in 94 was to monitor the two on one wire from pcm that if either of the sensors produced the wrong voltage code 43 is set... now we have the pcm watching each sensor individually and we get P0332/0327.
With sensor plugged in KOEO should have 1.5v. KOEO unplugged 5v. Voltage is pulled down then increases with a knock sound.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Well I don't know what Koeo means, but after testing both senors and rewiring everything returned to normal.
The sensor wire did have 5v unplugged. Did not check connected.
Watch out for the rear sensor. It has a 3/8" thread.
Thank for your help
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