Dead battery- now a miss?

[homemade87]

Most likely the Alt is not charging . Probably why it is running bad on low voltage . Dead battery is a clue . Put your a meter on the battery while running and see what its doing . The L wire on the Alt could be a bad connection . This is what starts the Alt to charging . Check it close . The L wire on the Alt is the reason for the code . Still could be the Alt .

Let us know what the running volts are at the battery .