pbj2

2008 Chevy Avalanche LT. I have only 1 symptom so far. At first it would do this after it sits from 3 to 5 hours or overnight. Upon starting if the radio was on it would reset the clock back to 12. Always started with no hesitation but would do it every time. Had the battery load tested and that came back good. Alternator was tested too with 14.3v at idle. I checked the battery monitor sensor which is on the negative cable coming from the battery. It seemed loose to me so I zip tied it tighter to the cable. That changed it slightly for the better as it now only resets the clock after sitting overnight on start up. My next step is to check the grounding wires and straps for good connections and clean mount points if needed. My questions would be just how common this issue might be and if anyone knows if there are any TSBs specific to this issue?