When this happened to me, I changed my alternator/voltage regulator and it's been 2 weeks and no problems so far. Some say the voltage isnt being regulated properly and that is the problem. And some the the alternator is going bad. To avoid testing both units, I purchased the alternator, which has the voltage regulator built into it and changed it.

BTW, This is a 4.8is...year 2005 with now 60k miles.

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2005 4.8is. Blue ext, white int.