DTC U0164: Door Multiplex Control Unit Lost Communication With Climate Control Unit

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NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0), and then back to ON (II).
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC U0164 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections between the door multiplex control unit and the climate control unit or HVAC control unit.
From the BODY ELECTRICAL SYSTEM SELECT menu, select B-CAN CONTROL UNITS INFORMATION, and then select CHECK CONNECTED CONTROL UNITS.
Is the climate control unit or HVAC control unit detected?

YES -Go to step 11.

NO -Go to step 6.
Measure the voltage between body ground and climate control unit connector A (28P) or HVAC control unit 28P connector terminal No. 1.

Fig 1: Measuring Voltage Between Body Ground And Climate Control Unit Connector Or HVAC Control Unit Connector Terminal No. 1
Courtesy of AMERICAN HONDA MOTOR CO.,INC.

Is there battery voltage?

YES -
- With climate control: Go to step 7.
- Without climate control: Go to step 10.
NO -Go to step 8.
Measure the voltage between body ground and climate control unit connector B (16P) terminal No. 16.

Fig 2: Measuring Voltage Between Body Ground And Climate Control Unit Connector Terminal No. 16
Courtesy of AMERICAN HONDA MOTOR CO.,INC.

Is there battery voltage?

YES -Go to step 10.

NO -Go to step 9.
Turn the ignition switch to LOCK (0).
Check the No. B16 (10 A) fuse in the under-hood fuse/relay box and the No. C26 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Are the fuses OK?

YES -Repair an open or high resistance in the No. B16 (10 A) and/or No. C26 (7.5 A) fuse circuit.

NO -Replace the fuse(s). If the fuse blows again, repair a short to ground in the No. B16 (10 A) and/or No. C26 (7.5 A) fuse circuit.
Measure the voltage between body ground and climate control unit connector A (28P) or HVAC control unit 28P connector terminal No. 12.

Fig 3: Measuring Voltage Between Body Ground And Climate Control Unit Connector Or HVAC Control Unit 28P Connector Terminal No. 12
Courtesy of AMERICAN HONDA MOTOR CO.,INC.

Is there less than 0.2 V?

YES -Go to step 11.

NO -Repair an open or high resistance in the ground wire or poor ground (G403).
Turn the ignition switch to LOCK (0).
Disconnect the power window master switch 37P connector.
Disconnect climate control unit connector A (28P) or HVAC control unit 28P connector.
Check for continuity between power window master switch 37P connector terminals No. 28 and No. 30 and climate control unit connector A (28P) or HVAC control unit 28P connector terminals No. 26 and No. 28 respectively.

Fig 4: Checking Continuity Between Power Window Master Switch Connector Terminals And Climate Control Unit Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO.,INC.

Is there continuity?

YES -Replace the climate control unit (see SUNLIGHT SENSOR REPLACEMENT ) or HVAC control unit (see HVAC CONTROL UNIT REMOVAL/INSTALLATION ).

NO -Repair an open or poor connection in the B-CAN wire(s) between the door multiplex control unit and the climate control unit or HVAC control unit.