Suddenly hearing the alternator

So, a couple weeks ago I started hearing the alternator (I assume- pitch increases with rpms). It wasn’t there before. Bad ground?

 

Are you hearing it through the radio speakers? If so, it’s it the same on every audio source?

 

yes and I need to verify.

 

Factory radio or aftermarket?

 

Factory, but with after market speakers, dsr1 and 2 amps.

 

I would check your ground connection to the chassis.

 

Start with the ground cables under the hood. Don't just tighten, take them off and clean the connections. Do you see any flickering of the dash lights at night?

 

No flickering lights. The ride is only 7 months old so loosing ground has me confused, but it’s the obvious culprit.

 

A bad crimp on a cable, a bit of corrosion somewhere, or maybe just a bolt that didn't get tightened properly could be the culprit. It's odd, but not the oddest problem I've heard of with a new vehicle.

 

If youre using the stock HU, switch the function that increases volume with speed to off. I cant remember where it is, but its in the setup menu somewhere. Likeliness is that it is on and the increase in output voltage from the HU is bringing up the noise that the amps are generating. If that helps the issue Id recommend checking you amp grounding. Make sure to remove any paint from where the ground is secured to.

If that doesnt help, check your amp gain settings. Dialing those down should reduce the noise floor. Increasing the gain on your amps obviously will increase all noise, pushing the gain past being matched to the input voltage will cause idle noise to be increased in a way that is can be heard at all times. Couple that with the setting that increases volume as you increase speed can translate to a constant noise. Hope that helps.

 

In the 2nd Gen trucks the setting is called Auto Sound Level (ASL).

I've also read that with the factory head units that the Bluetooth functionality is active even when the head unit power is turned off and that could be the whine source with speaker/amp upgrades (my situation). If you connect your phone to the Bluetooth and turn the stereo off, you can still use your phone through the stereo. Turning off the Bluetooth radio may by possible, but I think that the setting is very buried and I have no idea where to even begin to find it on the newer gens.