[RallyDRock]

mine dont dim but do flicker. im going to try adding a capacitor to the power line to see if it helps. it is definitely from the alternator because it changes with engine rpm and electrical load.
along with the generator=DC and alternator=AC the alternator energizes the armature (moving part) to control the output via voltage regulator. a generator energizes the stator (non-moving part).
the diode trio/bridge rectifier convert AC to DC and try to flatten out the bumps. Apparently it doesn't do a good enough job because there is some power fluctuation going on. Now this could raise a concern for those that are running carputers, laptops, or other sensitive electronic equipment. In that situation a DC/DC converter should be used.

the dimming when the brakes are pressed is most likely a poor ground somewhere in the brake lamp circuit, could be the brake switch by the pedal, the wires going to the bulbs, or anywhere else in the circuit. consult the wiring diagram in the service manual to pinpoint the grounds and their locations.