Was on the highway earlier and suddenly had a really strange whine happening from what seemed line under the dash. I pulled over, and I could feel the pedals vibrating a bit from it, as I stopped the noise got pretty quiet but was still there. I couldn't see any issues in the engine compartment, and the noise was not very loud out there. inside the cab it was very audible and seems connected to the engine RPM. If I revved the engine slightly the noise would go loud then soft as the RPM of the engine rose and fell I will include a link to a video of it. I have no idea what it could be or where to start searching to ensure there aren't any major issues. I didn't get any check lights or such. I got back on the highway to move to a safer place and the noise stopped about a half mile down the road and has not returned. Any ideas?


Truck stats:
2003 Suburban LS
8.1L Vortec Engine
about 140k miles on it
(if theres anything more that may help just let me know)

 

possible bad pulley bearing or alt, ps ac compressor bearing...remove both belts and run the engine briefly. if the noise is gone; spin all the pulleys by hand to find the noisy one.

 

Noises in the engine compartment can be transferred to the interior and sound louder inside the cab. I had a wire in the engine compartment that was vibrating against an air conditioner line running into the dash and it sounded like it was originating in the dash. Do as tech2 suggested. Was the air conditioner running at the time?