Two weeks ago my "service column lock" message on DIC returned( I have had a Corvettes of Houston bypass for years working perfectly). At same time I found that the odometer would, without fail, show up on start up, as opposed to the DIC showing the last gauge selected. Then the column would have to be manually telescoped on startup instead of automatically positioning. My aftermarket stereo would intermittently reset the clock and erase my custom equalizer selections. Then a week later I developed a flicker in the headlights, a day later the headlights would suddenly lose 50% of their light for 30-40 secs and then return fully bright, only to recur off and on intermittently for the 13 mile drive home. None of the interior lights were affected. I spent several evenings studying the schematics trying to figure out a most likely cause. Checked relays, fuses, alternator and then decided to give the Optima Yellow top a charge overnight. In the morning charger showed full battery. Turned key and car was absolutely dead! I'm now having lots of bad thoughts about BCMs and voltage regulators/alternators and all manor of expensive fixes. In a hurry to get to work I reached in to give battery a feel and as I brushed the negative cable I heard the solenoids Fire. THE NEGATIVE CABLE WAS LOOSE AND NEARLY READY TO FALL OFF! Tightened it up and remembered BILL CURLEE's advice to spec the bolts to 11lbs given out in an earlier post. Cured. All of it. That's all it was.
The point of my rambling comment is simply that sometimes the simplest issue is overlooked and a lot of time, energy, and $$ spent on something that could have been quicker, easier and less time consuming. Keep it simple and listen to Bill Curlee!

 

Good advice!

Always check the easiest, most obvious stuff first. It's sounds pretty simple and basic, but it's surprising how often this rule is not followed when troubleshooting, whether it's a Corvette or any other vehicle.