Starting The Self-Diagnosis Mode

Turn ignition switch from OFF to ACC.
Press and hold the "DISP/CLOCK" switch and turn the volume control dial clockwise or counterclockwise for 30 clicks or more.

Fig 1: Identifying Disp/Clock Switch And Volume Control Dial
Courtesy of SUZUKI OF AMERICA CORP.

Then the self-diagnosis operates. A single beep indicates self-diagnosis mode is active.
Initially, all display segments will be illuminated.
Press each switch. When each switch is pressed, its name and communication code will be displayed
NOTE: CD player LOAD and EJECT buttons are not included in this test and will not change the display when pressed.