At key off engine off, I have an hum at the alternator. Removed the power lead and hum went away. Is this normal? The truck sits more than it is driven so I was charging the batteries and can hear the hum with hood up.

Don't know if this is normal.

 

The only thing that should sing to you on your truck, is your turbo. Especially since you have an '03.

I'd pull the alternator and have it tested as I've never heard of an alternator doing that.

 

What happened when you take the charger off, does the noise go away? is there sparks from the terminal when you unbolted it? How many amps are you charging the batteries at?

 

Sounds like a bad internal regulator. Try to find a shop that does electrical
work not an AUtozone or place that uses the computer tester. That thing is
useless because it does not run it very long and allow heat issues to show up.


Sean

 

Finally to alternator to the shop. Since it was an Auto Zone alternator, took it back there and got a replacement. Seems like every 2 years getting a replacement. The original one is 110 amps, moved up to 135 amps and they gave me $10 back. Go figure.

I would have thought the larger amp would mean more money but not in this case.