Someone else may know the exact number, but I a pretty sure it means your alternator is not putting out enought voltage to keep the batt. charged. Shouldnt cause any catastrphic event unless of course you are stranded in the south side of Chicago.
From what I've seen the on/off GEN light problem, while driving along, is the alternator starting to act up. I'd check that out. It's a little bit hard to do with a meter while the car is running. Every time you take a measurement, the alternator usually behaves itself. Best to have it shop tested.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!