Battery Voltage at Start-up.
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I never knew why that was happening when I first got my truck. I was watching the yard apes boosting all the trucks at the auction where I bought mine, they'd boost it, wait 30 seonds, pull the cables off, and the trucks would quit. I asked one of them why, and he said "the computer runs the alternator, and it won't let it charge till the motor's been running a while".
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What is the source of this info? I have a Ford bodybuilder's bulletin that says the PCM randomly selects one of the alternators while glow plugs are active. Did Ford reprogram the PCM to prevent lower alternator from charging somewhere along the way?
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Thanks for sharing that doc, David. Unless this bulliten was just wrong to begin with, I guess they did change something.
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That's interesting. It wouldn't be the first time that I've found errors in the service manual.
It is also possible that the '04 and maybe later was different, since that bulletin was published in '03. Someone with dual alternators would have to get out the VOM and do some testing to know for sure.
I'm pretty sure my original post is correct, though. That the single alternator system is not controlled by the PCM.
It is also possible that the '04 and maybe later was different, since that bulletin was published in '03. Someone with dual alternators would have to get out the VOM and do some testing to know for sure.
I'm pretty sure my original post is correct, though. That the single alternator system is not controlled by the PCM.
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I suppose their might be readable PID's from the PCM that indicate which alternators are turned on, but you'd need something like AutoEnginuity to read them.
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13.7 after the glow plugs shut off is good. Unless you're having some other problems I don't see why you need to do anything.
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I'm not too worried about the alternator but 11.4v with the truck off is considered a dead battery. If I'm not mistaken, a batteries resting voltage should be north of 12.5v to be considered good.