i have a 1999 malibu the battery light is coming on when i drive but the battery still reads good the light on the ac delco is green :banghead:
What is battery voltage at when the car is off, and what is battery voltage at when the car is running?
If you have access to a volt meter, do the following
Check the wiring connections between the battery, alternator, and grounds and make sure they are solid
make sure alternator belt or serpintine belt is tensioned correctly
Measure battery voltage with everything off should read approx 12.6 V
Start car, , engine running , major electrical loads off (lights, AC, radio, etc.) You should read between about 14 to 15 Volts. Turn on lights and AC. voltage will dip a little but should return to 14 to 15 Volts within a second after adding the loads.
Any voltage readings outside these values mean the alternator or voltage regulator is screwed up and further bench testing should be done. Since the Chevy Malibu's voltage regulator is internal to the alternator, the entire alternator would need to be replaced or rebuilt (approx $110 for a rebuilt alternator)
Auto Zone, Advance, and some other places will test the alternator free.