Oldsmobile/Buick Repair: lights dimming, dashboard lights, buick century

Question
Hello. I have a 1992 Buick Century with 63,000 on it. When I apply the brakes the headlights and the dashboard lights dim for a quick second and then come right back to normal. This happens each time I apply the brakes. The battery tests at 12 volts and when the motor is running it is charging at 14 volts.The local garage has no idea what to look for. The motor is marked 3300. Thank you for your help.  

Answer
hey ken, well this is a prob.but try this pull one brake light bulb at a time .see if this stops it the one that stops it is pulling too many amps or has a short in it.possibly a bad plug or connector.or possibly even a bad regulator in alt.there is always a small amount of dimming but if you are talking about an excessive amount.try turning different things off while driveing one at a time and try and determine just exactly what is pulling high amps .normally it will be the heater motor.good luck billymac