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

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 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/HVAC control unit detected?

YES -Go to step 9.

NO -Go to step 6.
Measure the voltage between body ground and climate control unit connector A (36P) terminal No. 18 or HVAC control unit connector B (16P) terminal No. 15.

Fig 1: Measuring Voltage Between Body Ground And Climate Control Unit Connector A (36P) Terminal No. 18
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Measuring Voltage Between Body Ground And HVAC Control Unit Connector B (16P) Terminal No. 15
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 8.

NO -Go to step 7.
Check the No. 36 (10 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?

YES -Repair an open or high resistance in the No. 36 (10 A) fuse circuit.

NO -Replace the fuse. If the fuse blows again, repair a short to ground in the No. 36(10 A) fuse circuit.
Measure the voltage between body ground and climate control unit connector A (36P) terminal No. 36 or HVAC control unit connector B(16P) terminal No. 4.

Fig 3: Measuring Voltage Between Body Ground And Climate Control Unit Connector A (36P) Terminal No. 36
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Measuring Voltage Between Body Ground And HVAC Control Unit Connector B(16P) Terminal No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V

YES -Go to step 9.

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 the climate control unit connector A (36P) or HVAC control unit connector A (24P).
Check for continuity between power window master switch 37P connector terminals No. 33 and No. 35 and climate control unit connector A (36P) terminals No. 36 and No. 35 or HVAC control unit connector A (24P) terminals No. 24 and No. 23 respectively.

Fig 5: Checking Continuity Between Power Window Master Switch 37P Connector Terminals And Climate Control Unit Connector A (36P) Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 6: Checking Continuity Between Power Window Master Switch 37P Connector Terminals And HVAC Control Unit Connector A (24P) Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

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

NO -Repair an open or poor connection in the B-CAN wire between the gauge control module and the climate control unit or the HVAC control unit.