Charging issues

2002 FORD FOCUS
207,883 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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ARMY MECHANIC
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Replaced the alternator with a brand-new one car only charges above approximately 2000 rpm's the new alternator was checked and works fine but it only charges above 2000 rpm's. cannot figure out what is going wrong with it.
Nov 29, 2017 at 8:01 PM
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MHPAUTOS
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Is the charge indicator light coming on at all? also, there are three VIN numbers i need to check, so can you advise the full car VIN please?
Nov 29, 2017 at 10:03 PM
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ARMY MECHANIC
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The charge indicator light comes on about one minute after starting up and stays on unless i rev the car above 2000 rpm's. The car listed above is the sE model with the Zetec DOHC. According to the belt routing diagram this is the VIN n engine. If that is not correct then all of the parts on it come from the VIN 3 engine.
Nov 30, 2017 at 6:51 AM
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KHLOW2008
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Check the crank pulley damper. It could be bad and freewheeling thus reducing the alternator turning speed.
Dec 1, 2017 at 5:48 PM
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MHPAUTOS
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not a lot can go wrong here, apart from a problem with the alternator, the PCM and cluster light are all that is involved. i would look at what KHLOW has suggested and also ensure all earths are okay. if that is all good, i would consider looking into a problem with the PCM.
Dec 1, 2017 at 8:21 PM
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ARMY MECHANIC
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Going to try replacing the positive cable from the alternator to the battery then going through all electric connectors and tightening them up first. Do not think the crank should be an issue since it has had a complete engine rebuild in the last two years and crankshaft and pistons were completely replaced with performance parts.
Dec 1, 2017 at 10:36 PM
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MHPAUTOS
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My feeling is a problem with the circuit, checking all the cables and terminals is a good place to start.
Dec 1, 2017 at 10:55 PM
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ARMY MECHANIC
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Thanks for at least trying to help me out mhpautos. i know a lot of my issues on my car does stem from the crankshaft and pistons, but this is one time it cannot be. My timing has to be two teeth a head of factory or else it does not fire correctly, but i know from experience that it will not cause this issue.
Dec 2, 2017 at 12:39 AM
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STRAILER
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Hello,

To me it sounds like you have a bad alternator even though it tests good. This happens when a diode starts to leak which dissipates at higher RPM. Please use AC Delco or Motorcraft when replacing the alternator.

This guide can confirm the failure under AC volt checking

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please let us know what you find. We are interested to see what it is.

Cheers, Ken
Dec 4, 2017 at 1:38 PM
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ARMY MECHANIC
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Positive cable fixed it
Dec 4, 2017 at 7:51 PM
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MHPAUTOS
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well done, thanks for using 2carpros.........
Dec 5, 2017 at 3:43 AM