Question about 1992 Ford F150 SuperCab

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Voltage guage showing low reading. Had alternator tested. They said it was bad. Replaced it. Only getting 13. something with engine running. 12. something with out running. A "guy" told me the new alternator is bad. Really? I noticed the big red cable on the battery post looks like the got really hot in the past. Could that be a low voltage problem?

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You can isolate the new alternator by starting the car and disconnecting the negative battery cable with engine running. Now measure the voltage at the positive terminal to a ground. This will be your alternator voltage under normal load (w/o battery). It should be 14-15 VDC and closer to 15 if it's new. If not, return the new alternator and try again. If the voltage is normal, try touching the negative cable back to the battery terminal and see if it takes it back to 13. If yes, maybe your battery has an internal short.

Posted on Aug 24, 2010


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