Speaker Circuit: Description

WARNING: This page is about a different car, the 2007 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.

When the vehicle has a built-in type amplifier, a sound signal is sent from the radio receiver to the speakers via the "Built-in Type Amplifier System" circuit.
When the vehicle has a separate type amplifier, a sound signal from the radio receiver is amplified by the stereo component amplifier and then transmitted to the speaker via the "Separate Type Amplifier System (for Coupe)" or "Separate Type Amplifier System (for Convertible)" circuit.

If there is a short in this circuit, the stereo component amplifier detects it and stops output to the speakers. Thus sound cannot be heard from the speakers even if there is no malfunction in the stereo component amplifier or speakers.