1999 Ford F-150 System overcharge on my F150

1999 FORD F-150
136,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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BLAZE45
  • ✓Experienced Mechanic
  • 380 POSTS
Bought an F150 with flickering lights. Tested the alternator at the auto parts store and voltage was jumping all over the place. Replaced the alternator with a rebuilt one. Did the same thing... Checked all the connections, they were clean.

Battery tested good.

Took out the alternator and swapped it out for another one from the store. Tested good at the store before I put it back in. Still have flickering lights. Dash lights, headlights. Voltage overcharge to the tune of 15.1- 15.8 consistently with both alternators.

What is my next step here?

Dec 26, 2013 at 11:11 PM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
clean the battery terminal ends an dbattery to engine ground and battery to body ground. if still over charging try another battery as the one in truck may be sulfated
Dec 26, 2013 at 11:19 PM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
check the fusible links tha ti've pointed out as well as the fuses. the links may be hanging on by one or two strands causing this.
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Dec 26, 2013 at 11:43 PM
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