battery light Comes on and off.. Any idea what it might be

Asked by Neim Mar 11, 2020 at 09:48 PM about the 2005 Mercury Grand Marquis LS Premium

Question type: Maintenance & Repair

I have a 2005 Grand Marquis and the battery light Comes
on and off while driving but it doesn't stall out or anything..
It actually runs really good... I just changed the spark plugs
to platinum plugs and put the big brass battery connectors
and still dose it. I also had the alternator and battery
checked and everything seems good with both.. Any idea
what it might be?

2 Answers

70,735

alt could have a short on and off.... but, Suggestion is check all cables and grounds. A cable terminal can have a bad connection between the cable and terminal, that you cant see, disconnect and do a continuity test, it should show little or no loss, and the battery ground where it bolts to block or frame . That randomness you describe leads me to think of cable connections

59,625

Since its an older car may can find a used Repair manual on auction site cheap, then look for procedures & step by step instructions. If testing the Alternator remove it to have it load tested instead of pulling the negative battery cable to avoid damage to electrical system. As said before check battery Cables & terminals need checked, if they are original May just be time to replace or if loose tighten and if corroded replace.

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