Electrical whine at idle
 

Anyone else get this? Ever since I got my car there has always been a distinct electrical whine coming from my engine bay, which changes in pitch according to slight changes in electrical load, such as the blinking hazard flashers or revving the engine slightly. I've also noticed that my cabin lights will brighten and dim barely enough to notice when the hazard flashers are blinking. Does this indicate poor grounding, a weak alternator, a failing voltage regulator, all of the above, or something else entirely? I don't recall noticing it on any of my old cars.

I get this whine as well. I swapped out from stock coils to BHR and the hum still emanates from the engine bay.

I haven't noticed anything "odd", but I would like to know why does it have that electric hum? Is it a normal function?

2009 RX-8 Sport - 22k miles. BHR Ignition.

Cant really say my S2 does it, yet, I would have been thinking Alternator load hum, is your Battery original still?, meaning in good condition.

Just checked my Miata, it does it under electrical load, lights, flashers, and it is only 2 years or so old.

I don't think I would worry about it.

a lot of cars the headlights dim when you hit the brakes.
a good solution is to use HID since its regulated and draws a lot less current.

My car came stock with HIDs, and yes, they work fine.

The battery was replaced late last fall. It went from noticeably weak to completely dead in the span of about two days.

The fact that the cabin lights dim when the hazard blinkers flash really seems like a grounding problem to me; I assume the alternator isn't too weak to do its job properly at idle, so the only other explanation is that its job is being made harder by poor grounding -- it has to work harder to push the required amperage. Perhaps I should invest in a Big 4 grounding mod, or whatever the equivalent is for this car. I hate the way carmakers cut corners by grounding everything to the chassis instead of using proper negative-voltage wires connected directly to the battery, and then they can't even be bothered to make sure the chassis grounds are clean and free of paint when they attach them. On my Passat, the negative battery cable grounding post was painted, I shit you not.