Inspection Procedure 11: The Picture And Sound Of External Input Are Not Played: 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:
Whenever the ECU is replaced, ensure that the power supply circuit and the grounding circuit are normal. (Check that the voltage is 10 V or more).
Fig 1: Audio And Video Adapter Communication Circuit Diagram