hatch182

Just wanted to follow up! Thanks Supreme Pizza, the noise suppressor worked!

Both. I can turn the radio up and hear the hum. I can then turn the radio off, and go pop the hood and the same noise is coming form the alternator. If I unplug the connector on the alternator while running, it goes quiet. The whining comes back when the electrical connector is plugged back in (while running). The alternator doesnt make any bearing noise and is fully bench tested. It even made the noise with the new alternator.

Thanks Supreme Pizza! I have one on the way, hopefully that solves the issue!

Thanks for the advice! I pulled the radio and ran a new ground to the chassis, it was a 12gauge wire. Here is the odd thing, the loudest part of the whining is coming from the actual alternator. It completely goes away if I unplug the electrical connector while running...and instantly comes back. I checked all of the body grounds, as well. Its the strangest thing I've ever seen!

I just purchased a 2004 GMC 2500 with a 6.0. The truck has 130k miles on it. The guy I bought it from told me the alternator needed to be replaced because it had a whine that would come through the radio. He had replaced the radio because he thought it was bad...but the whine did not go away. I replaced the alternator, but had the same issue. I then took the original alternator to be bench tested, and it tested good. I put it back in, but the alternator has a whine when accelerating and it comes through the radio. To troubleshoot, I unplugged the wiring clip while running...and it makes zero whine under the hood. If I reconnect the the wiring, it starts making an audible whine that sounds just like the sound coming through the speakers over whatever music may be playing. It is driving me crazy...has anyone else had this issue?