High pitch whine near firewall
2000 Intrepid 2.7l, 150k miles
I have noticed for about 3 months that a high pitch whine is eminating from behind the firewall area of the car. At first I thought it was electrical interference in the radio. However, eventually the noise persisted after the car is turned off. Strangely, after pressing the brake pedal the noise stopped when the car was off. This leads me to believe that its a vacuum leak of some sort causing the noise. Is this a common problem? Is there a known repair that can be made.
I have little hope, as while replacing the water pump outlet last week, the previous owner somehow managed to get a blinker bulb lodged in an intake port the last time the plenum was removed 30k or more miles ago.