I have a 1990 v6 pickup, lately
my brake and battery light have been coming on.
I have plenty of brake fluid, but they turn on together.
and eventually turn off after about 15mins of driving.

Does this mean my alternator is dying?
I have about 225k miles.
Also turn the car off and restarting it, does not make
the lights go away.

Any ideas???

thanks for you help!

Possible causes
Regulator failing
Battery failing
Alternator failing
Loose belt
Poor coroded connections
Some chain auto parts stores offer free testing of the charging system.

The alternator needs new brushes.

thanks!
I went ahead and just put in a new bosch remanufactured alternator from pepboys, $119.
Problem solve!

We had the same problem on our 94 Toyota 4X4 pickup. The Brake Light, Battery light, and Automatic Transmission light would flicker on whenever we would accelerate. Then a day or two later the truck would not even start. The alternator was bad, we replaced it and everything's back to normal.