Out of the blue my 98 GT battery light came on. I checked the voltage at the alternator and was getting like 12.xx, checked the voltage at the battery and was within +/- .x Checked the alternator and battery off my 97 the same as i did on my 98 and got 13.5 at the alternator and 13.xx at the battery. Figured my 98 has a bad alternator... So i took the alternator off my 97 and got the same reading of 12.xx and same reading at the battery. So i left the 97 alternator on my 98 and put the 97 battery in the 98 in place of the 98 battery, same results. Any ideas would be helpful while i search......