battery indicator light is on/off
 

so was driving my nice 06 4x2 5.4 f150 and the battery indicator light came on. the manual says that the battery is not charging properly. anyone know what might cause this to happen. my truck is just bout out of warranty and i dont want to get stuck with something thats gonna be expensive to fix right after the warranty is out.

bad alternator, worn belt, corroded terminals......................

turns out i had a bad alternator. anyone else had this problem? just curious how prevalent it was with the newer 150's