Scottrod

Hi, I am new to the forum and looking for help. I have a 2010 Chevrolet Cobalt LT2. 2.2 litre. I have a CIL of P0327. I have change the sensor twice, replaced the connector on the wires from the ECM, checked for continuity from the ECM plug in back to the connector. I tested for voltage from the ECM and was getting 3.46 volts to the sensor. However, sometimes this voltage drops to 2.5 volts when the wires or fuse box it moved around. No loss in continuity. The two things I need help for are:

What voltage should I see as normal output from ECM?

Is this a short to ground or faulty wiring causing the voltage drop? Not very up on the electrical theory.
Any help will be greatly appreciated as I have spend 6 hours yestetday trying to troubleshoot this and now exhausted my repair skills. From here the only option left is to bring it to a dealer to be hooked up to the answer machine.

Thanks in advance, Scott

Scottrod

Thanks for all the help people, not! Anyway I hope this helps someone else out. The wiring harness was worn through where it passed by the oil filter housing. It grounded out the knock sensor wiring .