imnotnotjoe

i have a 1993 chevy lumina euro w/ 82k mi

All of my lights dim when i hit the brake. Most noticable in park, i will step on the brake and my dash lights, head lights and dome light will all dim. Also, if my power windows are all the way up and i push the up button, my lights dim. The battery guague on the dash is usually at about the 3/4 mark, when i thought it was suppose to be in the middle. Also, when i hit the brake and the window button, the battery gauge drops down. is this normal?

also, my engine is making an unusually loud clicking/tapping noise at constant intervals with the engine. Pretty loud when idling. any ideas of what it could be

Retardo

The alternator could be undercharging or undercharging. If the guage is supposed to be in the middle, and it's at the 3/4 mark, it could be overcharging, which would mean that the voltage regulator would need to be checked.

Usually, if the lights dim when doing all this, it's the alternator not putting out enough charge. The lights may dim just enough for you to notice when the brakes/windows are applied, but they shouldn't dim so much that you can't see anything.