Knock Sensor Problems
05-25-2008, 11:47 PM
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Knock Sensor Problems I am having a problem with both knock sensors. Apperently they both took a **** on me at the same time. Throwing codes p0327 and p0332. I know they are both low voltage and that they should be replaced.
Well I didnt know I could make sure they worked without taking them out of the valley cover. I know some ppl have a problem with them rusting out but mine were still clean and shiney.
So I used an multi meter to check the ohms on them. They each read 99.8 and 99.6 which is within the "normal" range. SO I was like cool they arent broken. So then I test the ohms through the wire harness that I took off the car. What do you know they read the same thing.
So my question for you is. How do I check further down the line. I cant seem to find a diagram for the pin on the computer for the knock sensors so I can check that part of the wireing.
Also give me some more siggestions. I dont see how both of them would quit at once.
Well I didnt know I could make sure they worked without taking them out of the valley cover. I know some ppl have a problem with them rusting out but mine were still clean and shiney.
So I used an multi meter to check the ohms on them. They each read 99.8 and 99.6 which is within the "normal" range. SO I was like cool they arent broken. So then I test the ohms through the wire harness that I took off the car. What do you know they read the same thing.
So my question for you is. How do I check further down the line. I cant seem to find a diagram for the pin on the computer for the knock sensors so I can check that part of the wireing.
Also give me some more siggestions. I dont see how both of them would quit at once.
05-25-2008, 11:55 PM
#2
Theres a test chart around here somewhere, I got lucky and it was a sensor but the chart went on to trouble shoot the whole knock sensor wiring to the engine computer. Maybe someone knows where it is, or type the codes in a search.
EDIT: Well never mind here it is: http://www.gearchatter.com/viewtopic9363.php
EDIT: Well never mind here it is: http://www.gearchatter.com/viewtopic9363.php
05-26-2008, 12:34 AM
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I know that I have already read it a few times. I never really understood the AC voltage part so if somebody could explain that to me that wouls be great.
I checked ok to every step on that except 4 because I dont understand it.
I was hoping I could get a digram to I know what pins are what on a 01 pcm so I can go further up the harness to see if everything alse is ok since my sensors read within the right ohms.
I checked ok to every step on that except 4 because I dont understand it.
I was hoping I could get a digram to I know what pins are what on a 01 pcm so I can go further up the harness to see if everything alse is ok since my sensors read within the right ohms.
05-26-2008, 11:46 AM
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05-27-2008, 01:34 PM
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Have you been able to measure the ac signal yet?
The end of step 3 does not tell you to reconnect the sensor to the jumper harness, so you should have access to the sensor output.
You need a multimeter with a low ac voltage scale.
They want you to connect the black lead of your meter to ground, the red lead to the knock sensor pin.
Have someone tap on the sensor with a small screwdriver. You should see some activity on your multimeter. I'm guessing about half the scale, or 0.2v AC.
The reading will only be there while you are tapping.
The end of step 3 does not tell you to reconnect the sensor to the jumper harness, so you should have access to the sensor output.
You need a multimeter with a low ac voltage scale.
They want you to connect the black lead of your meter to ground, the red lead to the knock sensor pin.
Have someone tap on the sensor with a small screwdriver. You should see some activity on your multimeter. I'm guessing about half the scale, or 0.2v AC.
The reading will only be there while you are tapping.
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05-27-2008, 08:18 PM
#12
A piezoelectric crystal inside the sensor generates a small amount of voltage, less than a volt. Thats why step 4 says to put your meter at 400mV (thats 400 millivolts) the 00.0 volts scale is not sensitive enough to pick it up, in fact a cheap DMM is not sensitive enough to pick up a jump in millivolts at all, you might see something happen with even a old needle type volt meter set to measure millivolts. Most digital meters won't pick up a mV signal created by a tap, thats millivolts for less than a second, read your DMM specs, it should tell you what it's capable of picking up.
