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I would like to help with your Saab question.
The most common issue with the 9-3's stereo's is there is a fault in one of the optical bus causing the system to be inoperative. What that means is that all the modules in the stereo system must work in order for the stereo to work. Generally there is an amplifier that fails a lot (AMP 1) and causes a break in the optical net work. If all the fuses look good, the only real next step is to take the car to a good Saab repair shop for further dianosis. This can take a few hours normally- expect diagnosis to cost at least $200. Parts and installation will be additional and will vary on the failure.
The reason the turn signals don't sound is because the noise is created by the audio system and sounded through the audio speakers.
Please let me know if I can assist any further.