Battery light on dash?

KENJOHNSON

MEMBER
2005 FORD TAURUS
3.0L
V6
2WD
AUTOMATIC
89,000 MILES

I installed a new alternator and believed it was not working. I check the battery voltage at 12.3 volts. Started the car and the voltage did not rise to indicate alternator was charging. It was suggested removing the positive cable from the battery with the motor running. If the car shuts off it means the alternator is bad. I did and the car shut off.

Wednesday, July 10th, 2024 AT 1:58 PM

1 Reply

CANNON1349

MECHANIC
862 POSTS

Hello,

Yes, that is the initial check for a bad alternator, so you are on the right track. However, if you installed a new alternator, you need to be 100% sure the nut is secure on the hot wire, and that the wire harness connector is plugged in with an audible click. Are you checking this with a multimeter? The Fusebox in front of the battery contains something called a mega fuse. If you leave the ground lead on the battery and check for voltage on both ends of this fuse, that will be the first places to go in the event something blows. You will see two large red cables bolting to the side of the Fusebox, a plastic piece should slide up and out for you to loosen the nuts to remove the megafuse. Also taking out the megafuse you can test it with a multimeter and should have no resistance. If you see "1" or "OL" the fuse is blown.

Hope this helps,
William

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Wednesday, July 10th, 2024 AT 4:31 PM