I have a 2004 Si and battery light has permanently been on for awhile. Originally, it was a failing alternator so I swapped that out. The light stayed off for a day until we had a torrential downpour. I went through a massive puddle which cause the car shut tp off for 1 second, lights and all, then the battery light came back on. Figured belt was wet and it was slipping temporarily but I was wrong. Light stayed on until battery died. New battery and 2 alternators later, light still stays on and drains the battery.
Alternators all tested good outside of the car but battery isn't receiving proper voltage while running.
Brand new battery.
Alt fuse was good and replaced with a new one.
Grounds are good, clean, and tight.
Figure while I wait on replies, I'll run to the store and pick up a multimeter.
