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Ground Issue?

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I'm having an electrical issue with my wife's 08 Yukon XL. I've noticed for the last year that I get engine noise (alternator whine) through the stereo speakers. I've been unable to locate the problem.


About 3 months ago, I had to replace the battery. It was only a little under 3 years old so it was a warranty exchange. The other day, I notice the a/c was kinda surging. It was like the fan was going lower and higher without changing the settings (not auto). I just happened to try to wash my windshield and the wipers were moving really slow. After this I looked at the batter gauge and noticed it would fluctuate between about 10v to about 14v, but only when idling. Once I started to move it would stay around 14. Last night the headlights went out for a split second...kinda like a quick flash.


I took it to the auto parts store yesterday to have them check the alternator. Everything came back fine, except he said the battery was just a little on the low side and might need to be charged. Remember, this is a 3 month old battery. The charging system should keep it charged. The guy suggested I might have a ground issue. Thinking back to the alternator whine, this actually makes sense.


My question is where to start? Can I simply run a ground wire from the negative battery terminal to the fram or chasis. Any input is greatly appreciated.

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Search Big Three Upgrade and start from there. Best upgrade you can do to your charging system. Also, do not dismiss the battery yet, I had a battery that was a few months old also have a bad cell inside and I went on an TDY for two weeks and came back to a dead battery. Took it in for a test and the battery tester said dead cell and got it replaced again.

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Okay, Iv'e read up on the big 3 upgrade and, while I'm sure it's a good mod to do anyway, I want a way to test and find the source of what's causing my problems. I don't beleive the battery is the issue as I've had the alternator whine with multiple batteries. Keep in mind I have a bone stock nav system...no upgrades whatsoever.


The engine noise in the speakers is a classic sign of ground issues. Again, I'm wondering if running a sperate ground from the battery to the chasis (or frame) could be a way to troubleshoot the issue or do I need to run a new ground from the motor to the frame...or both?

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I did a little troubleshooting today and checked the voltage across the battery with the engine running. It was 14.5 - 14.6. I then checked across the battery to engine block and battery to chassis and got the same voltage. To be fair the problem wasn't happening at the time. The problem is intermittent.


Any ideas?

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Could take it in. I forgot about the voltage regulator which is located internally in the alt I believe so you COULD try replacing the alt first to see if that fixes your issue with not only the surging, but the interference you are getting from the alt itself. The alt is probably case grounded to the block itself but some have external grounds that are ran to the chassis or block. I think you might be able to return the alt back if it doesn't fix the issue so just something to think about.

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