2003 Ford Mustang Logo
Posted on Jun 02, 2009
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2003 Ford Mustang GT Battery Light

Battery light came on. Had battery & alternator tested in and out of vehicle. Both fine. Had corrosion on the terminals. Cleaned them & replaced. Still have problem. When car is running, radio on, headlights on & a/c the battery drains & car dies.

What could be causing this if not the battery or alternator?

2 Answers

gord storey

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  • Master 477 Answers
  • Posted on Jun 03, 2009
gord storey
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Your alternator should power everything when engine is running. Battery is only for start up. Test voltage with a multimeter when engine is running , should be 14V or more . Any less indicates low alternator output.

fordexpert

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  • Ford Master 5,692 Answers
  • Posted on Jun 03, 2009
fordexpert
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Take the car to an autoparts place that tests starter draw and cables. The meter they use can also measure current drain besides the starter. Turn on your lights and then measure the current flow. If the numbers are not ridiculous turn off the lights and turn on the A/C, blower on low. Gradually increase blower speed and note readings. Then have on lights and A/C blower on high, note readings. And if that does not pin point it, try the rear window defroster with everything else on. See what the readings are.

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If you need further help, reach me via phone at https://www.6ya.com/expert/ralph_2f0886b7d6af32ce

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