Electrical experts out there?

[BBHOE]

I have a 2007 Tahoe LT3, I've been having a hell of a time diagnosing this weird electrical issue, intermittently I will get a fault code for ignition voltage below 9V fault code P1682, no rhyme or reason to it sometimes it will come back once a week or every other day, battery and charging systems are both OK, only weird thing I noticed was at times my charging gauge will go to 16V, 14V, and 12V. I have a scan tool but it only reads faults and basic PID's.

Any suggestions?
Thanks

[Okla-by God-homa]

Answered this in your first post.