What and where should I check? on 2002 Jaguar Vanden Plas

Getting a battery not charging warning periodically.Drained the battery once and then went away again.

Asked by for the 2002 Jaguar Vanden Plas
2 answers
should be looking at alternator. sounds like its failing(either that or the battery has hit its life span). get diagnostic run to confirm or dismiss. tech. will advise.
have complete charging system ck for draw and charging