AMP Sound Signal Circuit between Radio Receiver Assembly and Stereo Component Tuner: Description
WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
The radio receiver sends sound signals to the stereo component amplifier. The amplifier then amplifies the signal, and the amplified signal is sent to the speakers.
If this circuit is open or shorted, no sound will come out of the speakers even if the amplifier and speakers are functioning properly.