Audio-HVAC Display Communication Line Circuit Troubleshooting

Turn the ignition switch to LOCK (0).
Disconnect HVAC control unit connector A (24P) and audio-HVAC display unit 16P connector.
Check for continuity between the following terminals of HVAC control unit connector A (24P) and audio-HVAC display unit 16P connector.
24P: 16P:

No. 11 No. 12

No. 12 No. 11

Fig 1: Checking Continuity Between Terminals Of HVAC Control Unit Connector A (24P) And Audio-HVAC Display Unit 16P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 4.

NO -Repair an open in the wire between the HVAC control unit and the audio-HVAC display unit.
Check for continuity between body ground and HVAC control unit connector A (24P) terminals No. 11 and No. 12 individually.

Fig 2: Checking Continuity Between Body Ground And HVAC Control Unit Connector A (24P) Terminals No. 11 And 12
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to body ground in the wire(s) between the HVAC control unit and the audio-HVAC display unit.

NO -Go to step 5.
Reconnect HVAC control unit connector A (24P).
Connect audio-HVAC display unit 16P connector terminals No. 11 and No. 12 with a jumper wire.

Fig 3: Identifying Connection Between Audio-HVAC Display Unit 16P Connector Terminals No. 11 And 12 Using Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to ON (II).
Press and hold the DEF button and FAN ON/OFF button.
Is the DEF button LED blinking?

YES -Audio-HVAC display unit is faulty, replace the audio-HVAC display unit (see AUDIO DISPLAY-USB ADAPTER CONTROL UNIT REMOVAL/INSTALLATION ).

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