Vmaxkid

Hi,

Hoping someone might be able to help me out.
As soon as I turn the ignition to on or start I get this high pitch noise coming from the speakers. It is intensified when I step on the brake or turn anything on in the car. It will not stop. So I pulled the dash apart and disconnected all the wires to my stock Bose stereo (The car is a 1989 if that matters). This did nothing to stop the sound. There is a wire that isn't connected to the radio but has a connector directly behind the radio. It is orange and the connector is grey. Once I pulled it apart the noise stopped coming from the speakers. BUT the radio will not play when it is disconnected. Can anyone tell me what this is and why I am getting this annoying high pitch sound whether the radio is on or off makes no difference.
I have a photo of the wire:

Gunho

Did you check it with a volt meter to see if it's hot? Could be the power wire from the alternator. Also I had stereo issues the other day. Popping and turning off and on when I hit the brakes. Turned out my alternator wasn't charging because it wasn't plugged in and my battery was dieing. Plugged the alternator back in and all is well.

Vmaxkid

I did check to see if it was hot. It is all the time even when the car is off. But why would there be a wire from the alternator running behind the radio? And better yet, why when unplugged would the stereo light but not make sound?

FWC

It's purpose is to supply power for radio station / clock memory which is why it lights up but does not work otherwise. I don't believe it comes from the alternator.

Vmaxkid

so I went out to the car today and went for a ride. The radio and all wires are out and unplugged. The orange wire (that doesn't go to the radio) that I disconnected, I reconnected. No noise. The entire ride, no frequency hissing noise. I come back, connect all the wires to the radio and the sound is back. I pulled the pink wire going to the back of the radio off and the sound went away. I put it back and had all plugs connected for about 5 minutes. I disconnected the pink wire and still get the noise. I took all the wires and disconnected just leaving the orange wire that does not pass to the radio connected. Still hissing even though no radio connected. I sat and listened, it is definitely coming from the speakers. I shut the car off and the sound is still hissing. I pull the orange wire and it stops.
So my question is, does something go to the amps on the Bose speakers that keep them energized or at least stay energized after the car has been turned off for a bit?