I have static in my AM radio in the Bronco. When the key is set to ACC, the radio works fine, but as soon as I set the key to ON (but not START), the radio produces a loud hiss that drowns out the audio of the station I have selected. the radio works pretty well in ACC, it can get a wide range of stations, but when the key is set to ON, whichever station is dialed in at the time is overcome with hissing or static.
What sorts of circuits in my Bronco can produce noise in the radio?
Remember, the noise is not coming from the ignition circuit because it happens while the motor is not even running. In fact, the noise remains the same after the motor starts, and does not change with engine speed.
The hissing does not sound like it comes from a motor (fuel pump), but I suppose it could come from a circuit that has a motor (fuel delivery).
The power source for the radio is hot when the ignition is in ACC or ON, but in ACC there is no noise. This means that another circuit that is hot in ON, but not hot in ACC has to be the source of my trouble. It's times like this when I wish I had a Factory Shop Manual.
Jerry B.?