2004 - 2008 F-150

05 f150 alternator

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Old 09-23-2017, 11:35 PM
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05 f150 alternator

My battery light was coming on intermittently so i had a local AutoZone run a test. The guy said its pushing 12.9 volts so the alternator was good but it's showing my battery is bad. Their batteries where 160. I found similar battery at Wal-Mart for 100. Swapped em out and still battery light goes on and off.

so I'm thinking with my luck on this damn truck lately I'm going to have to bite another expense and get an alternator. 200 plus bucks from auto zone or i can order an alternator from bd electrical through Wal-Mart for 85 bucks.

anyone know these cheaper brands and are they any good? Trying to save money as i have a lot of this and that coning up I fixing the truck. It's 4.2l v6.

appreciate any help or feedback on this. Thanks brothers. 2005 f150 4.2l v6
 
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Old 09-24-2017, 01:44 AM
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The guy said its pushing 12.9 volts so the alternator was good
No it isn't. Should be at least 13.8 volts when running.

Cheap reman alternators can't be trusted, make sure you get a good warranty with whatever you get.
 
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Old 09-24-2017, 08:33 AM
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Does the truck have to be running to check alternator? It was off he never turned on when checking battery and alternator
 
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Old 09-24-2017, 10:46 AM
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Originally Posted by Recoil9
Does the truck have to be running to check alternator? It was off he never turned on when checking battery and alternator
The battery is tested with it not running, and it should be load tested. It must be running to check the alternator.
 
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Old 09-24-2017, 11:02 AM
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I was told at Autozone that their less expensive "rebuilt" alternators were used and only the non-working parts were replaced.
 
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Old 09-24-2017, 04:37 PM
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I got my reman at O'Reilly with a lifetime warranty.
 
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Old 09-24-2017, 07:34 PM
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I took it to AutoZone and had the battery checked and the alternator. Both checked out good. The guy said he had a similar issue in his ford truck and it turned out to be an inline fuse further down a cable that attaches to the positive connection. He had 2 cables i have 3 connected to battery positive.

does this shed any light on anything?
 
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Old 09-24-2017, 09:27 PM
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Mine was doing that - and the alternator tested good. However, the test lied.

You may want to pull the alternator and get it bench tested.
 
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Old 09-25-2017, 12:10 PM
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I just checked the fuse links and the brown wire feels kinda mushy to me. I'm wondering if it's blown? I don't have a meter to test so wondering if there any other way to test before pulling the alternator out?
 
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Old 09-25-2017, 02:09 PM
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Meters are cheap.
 
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Old 09-25-2017, 05:36 PM
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First time i noticed this. The battery light gauge needle was always just a little past the middle mark leaning on the high side. The needle jumped all the way to high and the light went out.
the guy at AutoZone did say at one point the alternator was putting out high amps. Does that help narrow down any?
 
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Old 09-25-2017, 08:05 PM
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High amps or excessive voltage? Anything over 14.8 volts is excessive.
 
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Old 09-25-2017, 08:29 PM
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Not sure. I may try another place tomorrow and have it tested to make sure. He also said if that battery sat on the shelf for a period of time the alternator could be overworking to charge battery back up. But how long would it take to charge a battery back up?
 
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Old 09-25-2017, 10:00 PM
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Get one of these and monitor your system voltage.

https://www.walmart.com/ip/Universal...lack/543343659
 
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Old 09-27-2017, 08:20 AM
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Had another test done at o Reillys and the battery and alternator are both showing good. Battery fully charged and alternator charging good. Load tested with ac, lights and radio on and still good.

connections look good at battery and alternator as well. Fusible links from positive cable all feel hard so doesn't seem like any of them blew.

is there any other fuse that might have blown in the fuse box that relates toy alternator? A local shop said sometimes the problem is in the dash but couldn't get any more info.
 



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