This morning when I started my truck the headlights were flickering. Not just a little but like you were turning them on and off constantly. Didnt matter if low beams, high beams, foglights. all had the same problem. Even the dash lights did the same. The alternator still showed over 14v and pretty steady and didnt matter what rpm. Problem at an idle and while driving. Radio and all acessories off. Did it all the way to work. I get home today and check it and it isnt doing anything. Charging voltage stays above 14.4 with everything on. I have read similar problems on the older trucks but not the new ones. The truck has about 45k has a Optima Battery, all cables clean and tight and is a 2006 Sierra. Had it since new and no gremlins have worked on it. Any similar problems and what you did to fix it?

 

This was a common issue on most F-bodys, seems unusual for GMT800 that already has the AD-244 140amp Alt...

Amperage output is just as important as the voltage output. Putting DMM on your battery tell us very little...

Could be your bridge rectifier going out. (not enough amperage output)

Since you have checked your battery terminals for corrosion and loose connections, go have a reputable shop perform a charging system diagnostic.

let me know the outcome.

Trev

 

I had this issue on my Z28 and it was a loose connection at the alternator. Could also be a loose ground or faulty alternator.

 

Had found no loose connections or corrosion. Ended up changing the alternator for the hell of it and it fixed the problem. Same charging voltage as old alternator but fixed it immediately.