With Navigation

Disconnect climate control unit connector A (32P) and the audio-navigation switch panel 24P connector.
Check for continuity between the following terminals of climate control unit connector A (32P) and the audio-navigation switch panel 24P connector.
32P: 24P:

No. 3 No. 7

No. 4 No. 19

Fig 1: Checking Continuity Between Terminals Of Climate Control Unit Connector And Audio-Navigation Switch Panel 24P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 3.

NO - Repair an open in the wire between climate control unit connector A (32P) and the audio-navigation switch panel 24P connector.
Check for continuity between body ground and climate control unit connector A (32P) terminals No. 3 and No. 4 individually.

Fig 2: Checking Continuity Between Body Ground And Climate Control Unit Connector A (32P) Terminals No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to body ground in the wire between climate control unit connector A (32P) and the audio-navigation switch panel 24P connector.

NO - Go to step 4.
Reconnect climate control unit connector A (32P).
Connect audio-navigation switch panel 24P connector terminals No. 7 and No. 19 with a jumper wire.

Fig 3: Connecting Audio-Navigation Switch Panel 24P Connector Terminals No. 7 And No. 19 With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
Press and hold the front DEF button and OFF button.
Is the front DEF button LED blinking?

YES - The audio-navigation switch panel is faulty, replace the audio-navigation switch panel (see AUDIO-NAVIGATION SWITCH PANEL REMOVAL/INSTALLATION ).

NO - The climate control unit is faulty, replace the climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).