charging system dash light

2004 FORD EXPEDITION
250,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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CHUCK L.
  • MEMBER
  • 4 POSTS
my dash light showing a charging problem, and the computer display continuously display a problem. The charging gauge shows no problem. The auto electrical shop says everything is working fine, battery, alternator, etc. What do I have to do to fix this?
Oct 2, 2019 at 4:59 PM
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BMDOUBLE
  • ✓ASE Certified Mechanic
  • 1,139 POSTS
  • ASE Certified Mechanic
The charging system can pass all tests and still have a bad voltage regulator (integral to the alternator). Especially with aftermarket alternators! They just don't work very well! Has the alternator been replaced? I'd like to know before I get more in depth with diagnosis.
Oct 2, 2019 at 5:45 PM
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CHUCK L.
  • MEMBER
  • 4 POSTS
yes, according to the previous owner, the battery and the alternator were replaced. When I bought the vehicle and saw the charging light was lit, I asked, then took the vehicle to a shop and had the system checked. In the ten months I've owned the truck, I have never had an issue with a low battery or trouble starting, and the voltage gauge shows proper output of 13.5 volts, but the light stays on and the computer will give the check charging system warning every 15 or 20 minutes.
Oct 2, 2019 at 11:21 PM
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BMDOUBLE
  • ✓ASE Certified Mechanic
  • 1,139 POSTS
  • ASE Certified Mechanic
It could have an aftermarket alternator. I would either have this alternator warranty replaced or get a Motorcraft re-manufactured unit. This is where I would start before chasing down circuits that could take hours on end.
Oct 3, 2019 at 1:39 PM
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