How To Check For Audio System Condition

Turn the ignition switch to ON (II).
Make sure the audio system is turned off.
Push and hold the preset No. 1 and No. 6 buttons.
While holding the buttons, push the PWR knob to ON.
Release the buttons and the self-diagnosis begins.

Fig 1: Identifying Audio System Buttons
Courtesy of AMERICAN HONDA MOTOR CO., INC.
When you are in the self-diagnostic mode, pressing a preset button starts the diagnostic mode that is assigned to that preset button.
Display Specifications

NOTE: Any other diagnostic screens shown are for the audio manufactures use only.

Entire LCD lighting (press No. 2 button)/lights-outs mode (press No. 3 button)

Entire LCD lighting (press No. 2 button)/light-out (press No. 3 button) mode: Turns on/off the entire LCD to show if a LCD segment is stuck on or dead (off). If a LCD segment is stuck on, or is dead, replace the audio unit.

Fig 2: Identifying Diagnostic Screens
Courtesy of AMERICAN HONDA MOTOR CO., INC.

I2C-BUS communication verification status (No. 4 button)

NOTE: If any of the buses are faulty (NG), replace the audio unit (see AUDIO UNIT REMOVAL/INSTALLATION ).

Fig 3: Identifying Diagnostic Screens - I2C-BUS Communication Verification Status (No. 4 Button)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
The self-diagnostic function ends when you turn the audio unit OFF, or turn the ignition switch OFF.