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alternator or battery problem

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Old Mar 13, 2007 | 07:16 PM
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alternator or battery problem

Hello everyone, I have a 98 F-150 4.6, today when I was driving my ABS light came on. Then I noticed my battery guage was down at the bottom, around 8v. Then I put on my blinker and all of the guages went to the bottom. I stopped at the nearest parts store to check the battery and the voltage was low. Put in new battery and off I went, all guages and everything was fine. Well, I started thinking about it and thought was it the battery or alternator. I went and checked the voltage at the battery with the engine iff and got around 12.5v, with the engine running at idle not quite 13v. With a working alternator I should have 14.5v correct. poss. bad alternator?
 
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Old Mar 13, 2007 | 08:07 PM
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You can tell if the alternator is working by running the truck at idle and turning the lights and blower motor on. The gauge will dip but should recover and compensate for the load. If it can't hold it and goes below 12 then I would check it.
 
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Old Mar 13, 2007 | 08:16 PM
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Yea I tried it with a load and it held around 12v. but i thought that it should have been higher than that.
 
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Old Mar 13, 2007 | 08:24 PM
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Did the voltage pick up when you revved the engine?
 
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Old Mar 13, 2007 | 08:46 PM
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Originally Posted by Ultramagdan
Did the voltage pick up when you revved the engine?
I didn't have my aligator clips on my meter. I'm going to check it again in the morning.
 
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Old Mar 13, 2007 | 09:05 PM
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13-14.5 is normal out of the Alt. depending on load and engine speed, I'd check the connections and cables first.
 
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Old Mar 14, 2007 | 04:07 PM
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Changed the alternator today, all is fine. thanks
 
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