Originally Posted by bigblue4x4

First I would test the 2 wires with a multi meter,and look for the correct resistance.You need to pull the intake to get to the sensors(so test them first,it could be the wiring or pcm).First pressure wash the engine good,paying close attn to where the intake meets the heads(do not ask me why I know this,I will just say it took 3 hours to clean out all the dirt from the intake ports)You will need to disconnect all the elec connectors,the coolant for the throttle body,the 2 fuel lines(special tool needed),all cables,egr valve(1 bolt at intake and bend out of way)and there is a plastic tube that runs up the drivers side fuel rail to a valve on top of the intake in the front,squeeze the gray retainer,squeeze not pull(again don't ask).I think that it.
When you get it off it should be the back knock sensor(remember the multi meter)Replace it and torque to (I will find later),rtv the rubber plug ontop.Clean the intake and head gasket surface with a rag and carb cleaner(stuff small rags down intake ports)reinstall intake and electrical.
You will need inch-lb and ft-lb torque wrench,1/4inch drive metric sockets and med thread lock.I paid $34 for the intake gaskets,$54 for the sensor,and $17 for a Haynes manual(worth it).Note canadian $.
You can not increase the voltage,the sensor is what creates the voltage for the pcm,so if the sensor goes bad you need to replace it.First thing you should do is go to the dealer,talk to the service mngr and get them to scan the comp for the code,and get a print out on that code(should be about 5 pages on how to check out the sensor,well worth it,took 10 min and it was free. I will try to get the torque specs when I find my manual.

Originally Posted by Texas Terminator

the odds of it failing are slim. knock sensors are piezo crystals

Originally Posted by Texas Terminator

knock sensors are piezo crystals that generate a frequency, not voltage, that is analyzed by an independent circuit in the ECM, which decides if it is actually knock or not.

Originally Posted by bigblue4x4

Right,the crystal doesn't fail,the sensor rusts out.


In order for there to be a signal to the comp,there need to be some sort of voltage created.The GM service info that I got said use a multi meter on ac volt scale and tap the block looking for a voltage signal,and this was the same info that the techs at gm use.

Originally Posted by bigblue4x4

Intake torque,Step 1 44in-lbs,Step 2 89 in-lbs
knock sensor,I torqued it to 18ft lbs (double check with dealer)

Originally Posted by Texas Terminator

everything has some sort of voltage, it just reads frequequency. that's why you need to use the AC volt scale to measure it as it develops a sine wave signal. is that from a factory service manual? if so, what is the actual testing procedure?

Originally Posted by bigblue4x4

It is from the fact service manual,the same the gm techs use.
The actual testing procedure is.


"1. Connect DMM between the appropriate knock
sensor signal circuit on the sensor side and the engine block.
2. Set DMM to the AC voltage scale.

Important

Do not tap on plastic engine components.

3. Tap on the engine block near the appropriate knock sensor
while observing the signal indicated on the DMM."