just noticed this 2 days ago while driving at night (has done it every day since)... after cruising at about 35-45mph steady for a minute or so, all the lights (headlights, interior lights, ect) will start faintly pulsing and you can faintly hear when then pulse... if you have ever heard what a strobe light sounds like when it pulses, "pew pew pew pew pew" you can very very faintly hear that sound. if i slow down like coming to stop, then start accelerating again the car is fine it seems untill i start cruising at a steady pace after a minute or so... then it will start doing it agian. any idea?

 

Bad ground, alternator, or battery.

 

well im never lucky enough for something to be that simple. It just doesnt seem like any of that since it only does after at least a minute of steady cruising. I'll go have it tested anyway at the parts store and see what I find out.

 

Have your alternator and battery tested.sounds like the alternator is getting weak.

 

this^ when your driving vibrations fluctuate with speed something is loose. when it comes to cars most things usually boil down to something miniscule.