Question about 1986 Ford F150 SuperCab

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86 F150 Replacement Alternator not working!!!

The alternator in the truck was giving me problems (gauge needle was bouncing back and forth, headlights were dimming/flashing, checking with voltmeter showed an inconsistent flow of power would spike to 14 then down to 11 then back to 14. I took the alternator to Auto Zone and they tested it and said it was bad. I purchased and installed a new alternator but when I checked it with a voltmeter it did not appear to be charging. I took the alternator back and had it tested and it passed. I was told to replace one of the plugs (3 wire plug that goes to the stator) I replaced the plug but still no output. I have since noticed that there is a wire broken off near the fender well, I traced that wire back to it's source and it goes to the 3 wire plug I replaced. I don't believe this wire is the reason for the lack of output on the alternator because it looks like it's been broken off for some time. Any ideas on what this problem could be? Thank you in advance for any help you may be able to provide.

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  • pbrjunkie Feb 23, 2009

    I have already replaced the belt with a new one. The battery is clean and the wires all appear to be in good shape with the exception of the one mentioned earlier.


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I would check the drive belt and make sure all of the wires to the alternator and the battery are clean if the drive belt looks crank or worn replace it

Posted on Feb 23, 2009

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