I was thinking that might be a cause, so is there a value I can check or (other than an oscilloscope) check the 3x Signal? I registered RPM so I assumed both signals were good but somewhere online I heard the 3x signal was used for below 1200RPM or something. How easy is it to replace? (I have a lift at work)

And no faults get thrown for this failure?

 

Still curious, did you have any faults in memory?

 

these are a hall effect type sensor so there is not really much of a signal coming from them. What happens is a chunk of magnet or just a large piece of metal is on the crank, there is a coil of wire in the sensor that gets "excited" when the magnet or metal cross its path. there is a slight voltage generated by the sensor that the computer can read and know where the crank is located. A good Oscope should be able to pick up the varience but I could not tell you what the proper signal is supposed to be without first checking a GM manual.

And no I didn't get any codes until the sensor became so bad that it didnt work more than it did. I cant remember the code number but it was a long time getting it to finally trip the code. Once I replaced the sensor the car ran great with no issues.

Hope this helps.
Massey