I have a 2007 ltz 4x4 Tahoe and I love it. I'm getting a high pitch whining through my radio after the truck is driven for about an hour. It's pitch and duration is in line with engine RPM. The problem is intermittent and comes and goes. I brought it to the dealer and they replaced the alternator but the problem comes back. Sometimes it acts up when I put the turn signals on and after it cancelled out it goes away for a while. Like I said it's intermittent and they want me to bring it in when it acts up. That is sometime hard to do. I also noticed when I sit at an idle for about 15 min I get a slight dimming in the headlights for a split second. I'm not sure if this is related or not to my problem. Anyone have any ideas that might point me in the right direction? Thanks for your time...

 

This sounds like a bad ground connection somewhere, especially if it's intermittent. Have they looked at the radio yet? Intermittent problems are alway troublesome. Hard faults can be found. The ones that come and go are the problems.

 

I agree with hardin thicke, the problem is most likely a poor ground. poor connections can heat up with use and can make the connection worse, which explains why it doesn't act up untill you've driven it for a while.

 

Regarding the dimming of the lights. Shawn can verify this, but the charging system is an "intelligent " system. It will go thru different cycles including a desulfating cycle. I doubt the two are related. The noise you're hearing is coming from the alternator. Bad spark plug wires will also cause interference too, but that's more like a popping sound as opposed to the whinning noise you're experiencing. The radio has many sources of ground available to it, including the metal chassis it's enclosed in. But without a doubt, the radio has a separate ground output wire at its connector. If that wire path to ground becomes broken, the ground parth may become a circuitous route thru other compontents. Ground loops form and become an antenna for the spurious hash that is generated by the vehicle. If it were my vehicle, I'd look at the radio as your next step. That's the easiest vehicle component to replace. After that, I'd check the ground wire from the connector on the radio, to where the wire is attached to the chassis. This may be a long route, perhaps out to a common ground bus. Regardless of length, it's a direct route to a common ground point. That minimizes the hash in the radio.

 

I had a whining in my silverado, if you revved i up the whining got louder. That was with the stock radio. I put in an aftermarket and it was gone. That radio burned up on me. put the stock head unit back in, the whining came back, now i have another aftermarket head unit in now, and no whining. When i first got the truck i just thought it was the ac fans. Apparently theres something up with my stock radio. Prolly doesn't help you whatsoever, but thats my expierience with the radio whine.

 

Might watch the voltmeter and see if the whining occurs when it is charging or not.