Alternator issue? - Ford Powerstroke Diesel Forum
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Old 11-09-2013, 05:59 AM

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Alternator issue?

A week ago I had my tensioner explode, threw the belt 1/2 mile from home, made it home, repaired the truck, and noticed afterwards the voltage would drop to 12.5 on my scan guage while running, started checking into it and found one battery at 11.6 static and 8.7 under load passenger side, driver was 12.5 and 11.7 while cranking, placed battery in question on the charger and retested, 12.2 static and 10.8 cranking, took the truck down to autozone this am and had them test the alt came back bad diode, the guy doing the test didn't seem to know what he was doing IMO I explained to him twice that the truck needed to run for a min or so to shut the GP off, each time he tested right away. Don't want to spend 200 bucks if I don't have to, any recommendations would be good, while driving on the scan gauge the voltage runs from 13-14v, occasionally drops to 12.5 at idle but right back to 13-14 while driving
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Old 11-15-2013, 12:54 PM
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If that is the oem alt it's good to go.
Clean all of your cables and where they land. The driver side cable lands on the frame rail near steering box, make sure it's clean.

Some wheel brg grease is always good for battery cables and battery posts.

Another thing running a ground cable from the block near alt to pass negative post allows batteries to charge after starting.
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