New user here, got a 2002 Monte Carlo SS with the 3.8L in it, intermittently wont start (starts fine twice then the 3rd time it won't) i try all the bypass tricks, unhook the battery and re-hook it on, attempt to start it in neutral, I only have 6 Volts going to the starter field exciter when it wont start, pulled the ignition switch, cleaned it out, replaced the ignition cylinder, but every 3rd start it won't crank or anything, lights come on and all, need some help on what else i can try.

 

Sounds like it might be a BCM security issue . The ignition switch sends power to the BCM and after it confirms all systems are good the BCM sends a ground to activate the starter relay which then energizes the starter. I guessing the wire your testing is the one going to the BCM . When it does start is that the same voltage ? Good luck

 

I hooked up a code reader and im getting A U1016, related to the PCM, could that be the problem?

 

The code is indicating it is loosing signal. If you just replaced the ignition switch perhaps it's a bad one , usually how things work out for me . Good luck

 

try another battery, I had similar issue before turned out the battery, which was not very old had a bad cell in it !!?