Diagnosis Function

It can illuminate all the indicators (LED) in the multifunction switch.
It can check for continuity of the switches by sounding the buzzer when the multifunction switch is pressed.
It can check for continuity of harness between multifunction switch and rear control switch (audio), or steering switch (audio).
NOTE: When it checks continuity of harness between multifunction switch and rear control switch (audio), rear control cancel switch is in OFF position.