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Discussion Starter #1
I was walking through my garage and heard a buzzing noise and it sounded like it was coming from my 68 mustang. Sure enough, there was a little box in the front right corner of the engine bay kind of behind the horn that was making a humming/buzzing noise. I unplugged it and when I plugged it back in it stopped. I have a battery tender on the car but not sure if that has anything to do with it or not. What is this box for. I attached a picture of the part I am talking about.

D29C4180-246B-49CA-B122-DC1A65710CD1.jpeg
 

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That is the voltage regulator that limits voltage from the alternator. I run the electronic version, so I cannot tell you if it is normal to hum when the charger is attached. My guess is that it is normal with the original style.
 

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The original voltage regulators have some moving contacts and electromagnets inside so that's probably what was making the buzzing noise. Newer replacements are all electronic so they don't have any moving parts to buzz.
744482

The procedure for adjusting it is in the shop manual if you feel like doing that sort of thing.

I don't know why it was buzzing, but it looks like your cable is half unplugged in your picture so that's probably not helping anything (assuming it's not just unplugged while you troubleshoot).
 

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Discussion Starter #5
I had actually unplugged it. It had me concerned because my family is leaving for Florida in the morning and I don’t need anything happening while we are gone. I was worried something might be shorting our or something.
 

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I had actually unplugged it. It had me concerned because my family is leaving for Florida in the morning and I don’t need anything happening while we are gone. I was worried something might be shorting our or something.
Just to play it safe remove the negative battery cable till you can check out the electrical system.

yarb
 

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.... I have a battery tender on the car but not sure if that has anything to do with it or not. ......
crazy, but I would assume it's due to the battery tender energizing the VR, although I do not know the science explaining it
 

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That is the voltage regulator that limits voltage from the alternator. I run the electronic version, so I cannot tell you if it is normal to hum when the charger is attached. My guess is that it is normal with the original style.
your guess is incorrect. it should not make noise. he should clean the connectors & check the points inside.
 

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Discussion Starter #9
I’ll have to do that then. For now I’m just going to take the battery tender off and disconnect the voltage meter till we get back from our vacation. Thanks for the help guys.
 

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I’ll have to do that then. For now I’m just going to take the battery tender off and disconnect the voltage meter till we get back from our vacation. Thanks for the help guys.
No, leave the battery tender on, and disconnect the battery cables.
 
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