Hi,

In this thread it was a vacuum leak at an actuator and the whistle changed with engine speed: http://www.peachparts.com/shopforum/showthread.php?t=65000

In this thread they are suggesting it is the motor/regulator:
http://www.peachparts.com/shopforum/showthread.php?t=63734

Mike

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra