What are other causes of voltmeter overcharge....besides faulty alternator?

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  #1  
Old 05-29-10, 07:02 PM
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What are other causes of voltmeter overcharge....besides faulty alternator?

Can someone tell me other possible causes of overcharging alternator besides faulty alternator itself? I already had alternator replaced twice. The last time was March 2010.

I am still getting same symptoms: pulsating headlights, oscillating voltmeter needle, overcharge at 14.6-14.8 volts, and lights brighten when I give it gas.

Thanks,
Dave
 
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Old 05-29-10, 07:58 PM
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have you tried-clean/add grease to the battery cable lugs.?
the voltage regulator-in the alternator-is looking at battery voltage.
corrosion at the lugs,or grounds,is a usual culprit.
also-peel the insulation back on both batt cable lugs-look for any 'green/acid-oxidized coloring-problems/if -so replace/repair-as needed-do not cheap out on the"$"-it will only bite you

make & model will help
 
  #3  
Old 05-29-10, 07:58 PM
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Depending on year make and model of car/truck you could have a external voltage regulator that will cause all the above you mentioned and the alt. wasn't the problem at all. If an internal voltage regulator I have had 5 bad in a row from my parts supplier.(they got a bad batch) and that could be the problem.
If a newer 06 and later most manufactures use the ecu to control charge rate eliminating the regulator all together and you will have to go to a shop with a tech 2 scantool or dealer for a reflash to correct this problem.
Bottom line let me know what we are dealing with (year make model ) and I try and point you in the right direction.
 
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Old 05-29-10, 08:12 PM
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It's a 92' Ford Ranger Supercab with 2.9 V6

The battery cable, posts and terminals look clean from the outside. But I will reapply dielectric grease or "purple stuff"

The voltage regulator is included with and attached to the alt on my make/model. It's a rebuilt alternator and I am told it's common for rebuilt ones to be faulty. But it's been replaced twice now.
 
  #5  
Old 05-29-10, 08:21 PM
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as stated/pull back cable insulation-look for green oxidiation/
'look' for ,or make /missing body to eng ground
(10 guage wire will make a ground strap/!! if it gets hot/melts-you have a serrous ground connection problem!!

just currious- is this the same ranger -in the forum ,that had several eng replacements??
 
  #6  
Old 05-29-10, 10:31 PM
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I checked cable insulation and it was fine. I will check body to engine ground tomorrow morning and report back. Thank you for your suggestions

Where do I find body to engine ground?

Could this be a defect with wiring?

Yes this was the Ford Ranger mentioned in earlier postings that had issues with remanufactured engine. That has been resolved. Lifters were replaced and original lower intake manifold was put back on. I am not hearing the valve sounds anymore. I also had an engine oil analysis done and the lab results came back normal with no signs of anormal wear. I am monitoring to make sure there is no recurrence of earlier symptoms.
 
  #7  
Old 05-30-10, 08:12 AM
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that is why i ask,they could have left the ground cable loose/
put it on a dirty location
 
  #8  
Old 05-30-10, 12:01 PM
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Newtofta, I followed up on your recommendations.

I crawled under the truck and looked around for this engine-to-body ground for quite some time. The closest thing I found was a metal cable bolted to the frame under the engine. It was clean metal-to-metal contact.

I also cleaned the battery posts and terminals. There was a tiny bit of corrosion. Then I coated with dielectric grease and tightened.

By the way, the positive terminal was barely even tightened when I removed it for cleaning. Would this cause the overcharge condition?

I have another question I'll send privately on this website
 
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