mrbreez55

I kept getting trouble code P0332, low input knock sensor. Replaced both KS and short harness. Checked ohm resistance, 100.0 and 100.5, in spec. Other forums I have chatted with say there is supposed to be 5 volts coming from the PCM to the KS. There is zero volts coming from the PCM. I bought a PCM from Flagship 1. Install was routine. I still get the same code. All the, the truck runs fine, no ping, missing, hesitation, no loss of performance or fuel economy. There is still zero volts from the PCM. Does anyone know for sure that there is supposed to be 5 volts from the PCM to the KS?

tech2

some piezo sensors generate their own voltage. post your year, make model engine and I will check for you.

mrbreez55

'07 Silverado classic. 5.3 flex. I replaced original KS with delco sensors. Are you saying the knock sensors create voltage while the engine is running? If that is the case, the trouble code must be caused by something else.

tech2

they create AC voltage when they detect knock. I'll look up the code and get back to you

mrbreez55

I am not getting ac volts, engine running, as I tap on the valley plate with a ratchet extension. I sometimes get an intermittent evap canister/purge valve code. That valve doesn't open right away even when there is 12+ volts to it. When it does open, a few minutes later, it is rapidly pulsing open-close, open-close. I don't know if this has anything to do with it. Again, the truck runs fine. Having that light on annoys the hell out me.I really like the truck and don't want to have to trade it off.

tech2

evap will have nothing to do with a knock sensor code. the purge won't open right away...its supplied battery voltage in run....its grd controlled by the pcm. if you want that diagnosed post that code.
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the knock sensor code....ohm check the wiring from the sensor connector to the pcm. it should be close to zero ohms. if that is good, by a gm knock sensor and install it. or swap the knock sensor from the other side and see if the code follows the sensor...if it does...you know the sensor is the fault.

mrbreez55

I checked both lines when I installed the PCM. I had zero resistance on both lines. I have already installed 2 new Delco KS and the short harness. I get ohm readings of 99.6 and 99.7 on the new KS. It's just hard to believe one of the new sensors is bad. Possibly overtorqued? I will try to swap the wiring and see if that throws the code for the other sensor. I appreciate your info. I really like this truck, this little problem is annoying and I am determined to get it right. Thx.

tech2

all it takes is the sensor to be dropped and its no good.

mrbreez55

It appears that 1 of the new AC Delco sensors I installed was bad. I took 1 of the original sensors that was not bad and installed on the front of the cylinder head, ran a cable to it, and so far after about 8 run cycles I have not had any trouble codes. I just didn't want to believe that new sensor was bad. I hope this info may be helpful to others.