P0332, Knock Sensor Low Voltage

[chriskat01]

The problem moving to the other knock sensor wire shows it is indeed a bad knock sensor. Dont forget to swap your depinned wires back to their original place so you can keep track what a new code is pointing at later in life if another knock sensor were to fail. You can hookup a knock sensor but not install it. The only problem is that if you get engine knock then the sensors likely will not detect it and then your spark timing wont be retarded to stop the knock condition. Engine damage can happen then.
The sensors can be bench tested right out of the box on a workbench to verify a good part too.

Okay, how do I bench test a knock sensor?

I'm guessing connect the wiring harness, hook up a volt meter and tap the sensor on a hard surface? Or something like that.

Thanks for your help.
Jeff

 

[Fless]

 

[chriskat01]

I finally got time to work on the truck. Replaced the bank 2 knock sensor. I tested the output voltage on both of them before replacing bank 2. Bank 1 I could only get about .150 Volts AC when I hit the top of the block, or whatever they screw into. Bank 2 I got about .05 Volts AC. So I replaced bank 2 and it went up to the .15 to match bank 1. I'm hoping the low voltage is due to the limited vibration I can generate on a mass as large as the engine.

Drove about 20 miles so far with no codes. Here's hoping.

Thanks for the help on this issue.

 

[chriskat01]

So during all of this I started getting Service 4WD. I ohmed out the switch, based on what I could find on the internet, and it seems good. I cleaned the ground's behind the drivers side front tire. I don't have a code reader that will read the control module codes and it looks like I'd need to pony up $1700 to get one. Any thoughts on this issue.

Thanks again.

 

[Fless]

You can get a Tech 2 for about $300; it's the GM tool for these trucks. Chinacardiags has them right now for $229 plus $74 shipping.

Cheap GM Tech2/ Saab Tech2 Diagnostic Scanner Full Package

GM TECH2 Scanner Full package comes with free TIS2000 Software, you can choose one kind of software for GM, SAAB, OPEL, SUZUKI, ISUZU, and Holden.

www.chinacardiags.com

 

[rockola1971]

You can get a Tech 2 for about $300; it's the GM tool for these trucks. Chinacardiags has them right now for $229 plus $74 shipping.

Cheap GM Tech2/ Saab Tech2 Diagnostic Scanner Full Package

GM TECH2 Scanner Full package comes with free TIS2000 Software, you can choose one kind of software for GM, SAAB, OPEL, SUZUKI, ISUZU, and Holden.

www.chinacardiags.com

And now is the time to be buying test equipment clones like the Tech 2 from china! The Dollar is much stronger against the Chinese Yuan! So you get more for your money and pay less for the same equipment! This is why prices have came down so much on aliexpress, alibaba and the like.

 

[chriskat01]

I wanted to say thanks to everyone for their help. I've been driving for a little over a month now and no knock sensor codes; hope I'm not jinxing myself .

Also, bought the Tech 2 from chinacardiags to read the 4WD code. It was C0327 so I replaced the motor encoder ring, hopefully that is now fixed.

Thanks again,
Jeff

 

[Pcpurvis]

So during all of this I started getting Service 4WD. I ohmed out the switch, based on what I could find on the internet, and it seems good. I cleaned the ground's behind the drivers side front tire. I don't have a code reader that will read the control module codes and it looks like I'd need to pony up $1700 to get one. Any thoughts on this issue.

Thanks again.

My 02 Yukon SLE has just joined the knock knock club (240K miles); after reading every post on every forum as well as viewing every video on YouTube regarding the random PO 0327 code I made my choice to isolate the sensors from the ECM to confirm the harness and ECM was throwing false codes due to corrosion or connectivity. I inserted 2 110k ohm resistors in place of the sensors and connected them to ground using the harness connector (female side connected to the ECM). I rang the sensors on the male connector and bank 2 was 109k ohm and bank 1 was 38k ohm ( matched the 327 code). So it looks like bank 1 knock sensor has degraded - the ECM must be sensing higher bias current than expected or normal. If it was just losing connection to frame ground due to corrosion it would have higher resistance and a much lower resonance AC voltage output. So just to further confirm the circuit integrity and ECM the code hasn’t reappeared since I installed the test resistors (40 miles of city driving). Tomorrow I plan on purchasing a single AC Delco knock sensor and temporary jumper it to bank 1 (cut out the original bank 1 ) and mount it in an available tapped hole next to the water pump. This will give me confidence to continue with the repair knowing the true issue is the sensor.
Now the only concern is getting a set of good sensors; at least I have a test bed to get each for a time before going through the effort of taking the top of the engine off and on.

Any suggestions on a manufacture? I leaning on AC Delco.

 

[OR VietVet]

Genuine GM sensors or AC Delco and get new harness.

Welcome to the forum @Pcpurvis

 

[Pcpurvis]

Genuine GM sensors or AC Delco and get new harness.

Welcome to the forum @Pcpurvis

Thanks @ Or VietVet will do.

 

[Pcpurvis]

Thanks @ Or VietVet will do.

Update
After running with the resistors for several days with no codes I can be certain that the PCM and harness wiring is good. So all points to a bad knock sensor. So to further isolate bank 1 I cut the dark blue wire on the manifold side of the knock sensor harness connector and wire nutted the 110K ohm resistor (facing the PCM) and connected the other end to ground; this leaves bank 2 as original. So far (3 days and counting) all is good no knock sensor DTCs.
So I am leaning towards replacing bank 1 and relocating it external on the block near the right front side next to the water pump.
Is there a relearning process when replacing the knock sensor? Are there any potential issues or risk with me relocating it?

Thanks in advance.
Chris

 

[Pcpurvis]

I don't know the voltage I'm getting. I'll have to check. Any idea what the voltage is supposed to be?

No voltage output from a knock sensor unless you induce a vibration (hit your block with a hammer-tap it). You will only see AC voltage proportional to the amplitude of the induce strike. Typically on the bench vice you will see from 20 - 110 mv on a meter best to view on an oscope if you have one.

Couple of things:
Consider mounting the sensor externally until it proves 100%. There is a mounting hole on the left front side of the block near the water pump. Use a crimp ferrel female connector to connect to the sensor stud; then cut the original sensor wire from the in line connector (allow 4” or so to splice your new wire in place of the original sensor.
Clean the new mounting hole with a tap or bolt, then clean it with brake cleaner fluid. The threads are the connection to ground, dirty threads are likely your issue with the replacement sensors, either that or they are not sensitive enough (use GM certified sensors if you can).
The PCM connection could be corroded check to see if they are clean. I initially swapped my bad bank 1 sensor with a 100K ohm resistor and error code went away for a while (bank 1 was shorted to ground internally) eventually the PCM flagged it b/c of the lack of a signal (back to the sensitivity issue); I swapped the resistor to bank 2 and put bank 2 on bank 1 (at the connector) as I wanted to verify the PCM wiring and operation. Sure enough in a couple of weeks bank 2 was flagged by the PCM; I had my answers- PCM good, wiring good, sensor 1 bad, sensor 2 good. That’s when I decided to change sensor 1 and mount it externally.
Running 3 weeks now w/0 any faults; I might just leave it as is.
Hope this helps.