Flickering lights '01 Blazer

My 2001 blazer's lights (all lights...dash lights, cab lights, and sometimes headlights) flicker...get dim and then bright. What might cause this?

alternator?

hows your voltage look.
you can get the charging system tested for free at autozone...

Had the same thing with my '97.
Alternator tested good, and I had a new battery.
Belt Tensioner ended up being the culprit.
It was cracked, and eventually broke.
When that happened, there was no doubt what the problem was.
Replaced it, no more flickering.

HAd the same problem. Took the alternator out to check what regulator it needed and how to replace it, even removed all the screws that held it in until only the solder joints remained. Put it back together and back in and flickering was gone. Benn over 6 months.


Check all the connections.