Twofold question: I knew my right high beam was out. Yet before I could replace it, the left went out. Replaced the right, yesterday because I had purchased the bulb, and today, the high beam indicator starded flashing rapidly.
Second problem: When turning on my high beams, the low beams turn off completely. This was “fun” during the few nights when both high beams were out.
Buick Rendezvous 2002
does the owner’s manual show anything on this problem?
To be honest, I’ve never heard of a flashing high beam indicator before. When the indicator is flashing, are the high beams also flashing on and off?
What happens when you replace the other high beam and have two good bulbs installed?
LOL!!! The owner’s manual is the least helpful book that I’ve read. In an illustration, the knob that turns on the “head lamps” is called out, but that is about all.
Did you remove the bad left side bulb? Maybe the flashing knows it is gone?
low beams should shut off when you go to high beams. high beams are not “additional” they are “instead”. This is normal
Perhaps I am showing my age 
I remember when both lamps burned at the same time! Thank you for this information. Nope, the bad bulb is still in place. It will be replaced this evening. I hope that it is flashing to indicate that the bulb needs replacing, but I’m curious that it didn’t begin until the right bulb was replaced.