usermst9673

Okay here is the story my battery light came on while pulling into the driveway tonight. When i rev up the engine though the light goes away till it comes back towards idle. Does this sound like alternator is going south? Also what is the voltages that the alternator is supposed to be putting out. Will the battery light come on also if it is overcharging or just undercharging?

I know its a garbled mess of questions, but i am stumped.
Thx in advance for the answers!

usermst9673

forgot to add its on the 2000 gt!!

boss281

Were you messing with any of the electric connections in your car?

devongarver

look for 14v approx. across the battery when vehicle is running, 11-12v when vehicle is off, that would mean alternator is workign correctly. The alternator should put out a consistant voltage at any rpm, it is the current output that increases as the rpms increase. No matter what at a bare minimum i would expect to see no less than 13.5v while running or i would replace the alternator.

EDIT:Take your alternator off and take it to autozone they test it for free.

usermst9673

Well im assuming its the alternator now i get 12.65 when the car is off and only 11.9 when the car is on at idle thx for the help guys! ill post the results when i have it tested for sure at autozone

WhiteFoxGT

Half the time those tests will tell you a bad alt is still good...

Just replace it.. Probably have a bad diode

usermst9673

Well i just took the alt off and found out its a duralast from the previous owner who i have the name of!!!! Hopefully I can swap it out and get a free one Wish me luck!