Three instances today. Battery light came on for about 5 seconds then, off. Flashed like that 4 or 5 more times then was off. Later in the day same thing, pulled right into an O'Reilly Auto Parts, Battery and alternator tested fine. Final time tonight same thing but this time the brake light went on and off simultaneously with the battery light. My first thoughts are alternator going out. Had a new alternator put in 4 years ago (60,000 miles)

 

Have you check to be sure your alternator belt is properly tensioned and not glazed?

 

I have not but a new belt was put on 2 weeks ago

 

Check belt tension. They stretch!

Check voltage output from alternator



Telcoman

 

I don't think I've ever seen a vehicle with this style of belt tensioner that didn't require re-adjustment 2 weeks after driving. I set both my new belts at factory spec tension for new belt and they were loose to the point of squealing in 2 weeks.

It's possible (likely) either your voltage regulator is about to die OR you have loose/corroded connections on the electrical system. Disconnect battery/chassis ground/alternator feed and clean with a brush, apply some oxidation inhibitors and bolt it all back together. If there's still a light it's probably the alternator going out slowly, heat of summer brings out all the weak points in a vehicle.