Strange shaking/vibrating sound in gear D with headlights on

[bobyang]

Please check the Video: http://youtu.be/tnn6pse3vHM

0-21 second: D+headlight on (stronger shaking vibration sound)
22-26 second: P+headlight on (the sound disappear)
27-31 second: D+headlight on (the sound is back)
32-37 second: P+headlight off (the sound is gone again)


Strange shaking/vibrating sound in gear D with headlights on...
Anyone knows the reason and how to fix it?

I just changed an alternator 7 weeks ago from O'reilly. I notice it about 5 weeks ago. Finally, I just find the way to reproduce it recently. thanks