Negative voltage at knock sensor wtf, is this correct?
07-24-2012, 11:56 PM
#1
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Negative voltage at knock sensor wtf, is this correct? I went by Shbox's test procedure for testing the knock sensor at the pcm and at the harness of the KS.. PIN 22 D on the PCM read correctly at around 5v. I then tested at the knock sensor harness and it showed -5v... as in negative 5v and not 5v like the PCM showed.
This was all done by the book step by step, had the key turned on and the knock sensor unplugged.
Is this wrong and wtf how do I fix this...
PS - this is all being done because of my weird "knock sensor bank 2 circuit 2 low input" code I've been getting with my scanner.. won't set the SES light and won't show up as a primary code in the scanner, it only shows up when you dig into "enhanced DTC's". My car has been hesitating bad lately especially at low RPMS and forget about going WOT, it breaks up and pops and this seems to be the reason why if it's ******* my timing up.
This was all done by the book step by step, had the key turned on and the knock sensor unplugged.
Is this wrong and wtf how do I fix this...
PS - this is all being done because of my weird "knock sensor bank 2 circuit 2 low input" code I've been getting with my scanner.. won't set the SES light and won't show up as a primary code in the scanner, it only shows up when you dig into "enhanced DTC's". My car has been hesitating bad lately especially at low RPMS and forget about going WOT, it breaks up and pops and this seems to be the reason why if it's ******* my timing up.
07-25-2012, 05:01 AM
#2
You're connecting the leads on your VOM to the circuit backwards, switch 'em around and it will read +5v.
My car had the same symptoms as yours, it was bad spark plug wires. I ran the engine in the garage at night with no lights on and sparks were leaking from all my plug wire boots. Installed a new set of wires and all is good again.
Don't know about the code you're getting, maybe it's a red herring in this instance.
My car had the same symptoms as yours, it was bad spark plug wires. I ran the engine in the garage at night with no lights on and sparks were leaking from all my plug wire boots. Installed a new set of wires and all is good again.
Don't know about the code you're getting, maybe it's a red herring in this instance.
Last edited by guppymech; 07-25-2012 at 05:08 AM.
07-25-2012, 10:27 AM
#3
Looking at my '94 GM F-body service manual.
DTC43 is for the knock sensor circuit There is one more test shbox does not mention. With connector D disconnected from the pcm turn the ignition 'on'. check for voltage at wire D22 of the disconnected connector. If there's voltage the circuit has a short to +, Zero volts would be normal without the pcm setting DTC43. If DTC43 set check:
faulty knock sensor connection or faulty KS modual or faulty PCM.
You're description of KS bank 2 circuit 2 sounds like the description of the O2 sensor circuit faults.....are you confusing the two sensor systems? The F-body LT1 only has one KS. The Caprice and Corvetttes have two knock sensors, your sig doesn't say what you have.
DTC43 is for the knock sensor circuit There is one more test shbox does not mention. With connector D disconnected from the pcm turn the ignition 'on'. check for voltage at wire D22 of the disconnected connector. If there's voltage the circuit has a short to +, Zero volts would be normal without the pcm setting DTC43. If DTC43 set check:
faulty knock sensor connection or faulty KS modual or faulty PCM.
You're description of KS bank 2 circuit 2 sounds like the description of the O2 sensor circuit faults.....are you confusing the two sensor systems? The F-body LT1 only has one KS. The Caprice and Corvetttes have two knock sensors, your sig doesn't say what you have.
07-25-2012, 02:18 PM
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Nope, it's the KS, I just found out (posted another thread) someone put a 94-95 PCM in my 97 and probably didn't put in the 94-95 knock sensor, which is why I've been having all these problems!
I put in the LT4 knock module and it seems to have fixed it, but I'm pretty sure I still need to go out and get a 94-95 knock sensor to work with the pcm
I put in the LT4 knock module and it seems to have fixed it, but I'm pretty sure I still need to go out and get a 94-95 knock sensor to work with the pcm
07-25-2012, 03:40 PM
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That's what I'm trying to figure out in my other thread now, what to do about having this 94-95 pcm in my 97.. if I should just keep it and it's ok to run like this, or if I should go out and get the matching 97 PCM..
If all it is is a simple knock sensor swap to the 94-95 and everything else will work fine, I'm not worried... but I'm planning on getting a dyno tune next week sometime so I want to be sure everything is alright.
If all it is is a simple knock sensor swap to the 94-95 and everything else will work fine, I'm not worried... but I'm planning on getting a dyno tune next week sometime so I want to be sure everything is alright.
