I have a 2002 WRX and replaced the alternator in the car about 2 maybe 3 months go at most. Well driving home from work a few days ago I noticed the voltage being put out well idling and at highway speeds would jump from 14.4 all the way down to 11.5 volts. When ever the volts dropped to around 12.2 volts the battery light and the brake light would come on, along with the dash and head light dimming some. After a few seconds the battery and brake light would go out and the dash and headlight would come back to full. I replaced the battery in the car this past weekend thinking it might have had a cell going bad in it. But the problem started back up again half way to work I have also noticed a squeaking sound coming from near the alternator every time the lights would start to flicker. Could this be a sigh of the alternator going bad or some other problem?
How I was able to see the voltage well driving is a function from aftermarket stereo/GPS navigation system. One of its displays shows the voltage when the car is running.
Thanks for any help or advice you guys can give in solving the problem I am having.