Inspection Procedure 3: No Sound Is Heard From One Of The Speakers < Vehicles With Audio Amplifier >: Notes
WARNING: This page is about a different car, the 2008 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Before replacing the ECU, ensure that the power supply circuit, the ground circuit, and the communication circuit are normal. (Check that the voltage is 10 V or more).