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Discussion Starter #1
Battery light comes on only at idle, any bit of pedal and it goes off. Checked the 3 small wires going from the alt and they look ok, the large single has 12.6v when connected. However, when disconnected the post it was connected to only has 6v. Is this a sign of a bad alt? I think it is the original which would be 11yrs/145k miles!
 

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Are the batteries in good shape? Do you have a voltmeter? If so, check the voltage at the batts while running - should be 14.5 volts or so. Then pull the positive cables and check when not running - should be 13 volts to13.6 volts. Usually a defective Ford alternator will drain the batteries even when not running. Good Luck.
 

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Discussion Starter #3
batteries are good, less than 1 year old. Without the alt the batteries are at 12.6v

Alt output at the post on the back of the alt (which connects to the batteries) shows only 6v at idle, can't test at rpms until the wife comes home to rev the engine.
 

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alt

sounds like the alt or the regulator is going out. while running at idle, the alt should be putting out at lease 13v. if the alt gets replaced replace the regulator also at the same time. One night driving home from Dallas (the trip was like hrs one way) the alt light was a steady glow. We just replaced the external regulator be for that trip. Turns out the old alt burnt out the new reg and end up replacing the alt and regulator at the same time. Haven't had that problem since.:thumbsup:
 

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On my '96 there is a small square electrical plug on the top of the Alernator which "plugs" down into the alternator. This plug on mine would wiggle and over time get dirty, upon cleaning contacts and a very small wipe of dialectric grease to improve contact it's fine....

jrc
 

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Discussion Starter #6
will check the single plug - thanks.
 

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Discussion Starter #7
no change with cleaning the plugs. Does 6v at idle but just above 1000rpms it goes to 12volts output. I ordered a new alt from rockauto.com for $130 shipped. We'll see if that cures it...I do believe it is the original alt so it owes me nothing!
 
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