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Home >> Honda >> 2012 >> Odyssey EX >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Climate Control >> DTC Troubleshooting >> DTC B1237 or DTC indicator F and WINDSHIELD DEFROST: A Short in the Passenger's Air Mix Control Motor Circuit

DTC B1237 or DTC indicator F and WINDSHIELD DEFROST: A Short in the Passenger's Air Mix Control Motor Circuit

  1. Clear the DTCs with the HDS.
  2. Turn the ignition switch to LOCK (0), and then back to ON (II).
  3. Do the Self-Diagnostic Function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS  ) or the climate control unit (see HOW TO USE THE CLIMATE CONTROL UNIT SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS  ).
  4. Check for DTCs.

    Is DTC B1237 or F and WINDSHIELD DEFROST indicated? 

    YES  -Go to step 5.

    NO  -Intermittent failure. Check for loose wires or poor connections on the passenger's air mix control motor circuit.

  5. Check for DTCs.

    Are these DTCs also present; B121D or A and WINDSHIELD DEFROST, and/or B1234 or C and WINDSHIELD DEFROST, and/or B2968 or P and AUTO, and/or B2980 or M and AUTO? 

    YES  -Go to step  14.

    NO  -Go to step 6.

  6. Turn the ignition switch to LOCK (0).
  7. Test the passenger's air mix control motor (see PASSENGER'S AIR MIX CONTROL MOTOR TEST  ).

    Is the passenger's air mix control motor OK? 

    YES  -Go to step 8.

    NO  -Replace the passenger's air mix control motor (see PASSENGER'S AIR MIX CONTROL MOTOR REPLACEMENT  ).

  8. Disconnect the passenger's air mix control motor 7P connector.
  9. Disconnect climate control unit connector B (16P).
  10. Check for continuity between climate control unit connector B (16P) terminal No. 5 and body ground.
    Fig 1: Checking Continuity Between Climate Control Unit Connector Terminal And Body Ground
    G00523682Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short to body ground in the wire between the climate control unit and the passenger's air mix control motor.

    NO  -Go to step 11.

  11. Disconnect climate control unit connector A (28P).
  12. Check for continuity between climate control unit connector A (28P) terminal No. 25 and climate control unit connector B (16P) terminal No. 5.
    Fig 2: Checking Continuity Between Climate Control Unit And Climate Control Unit Connector Terminal
    G06968321Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short in the wires between the climate control uni tand the passenger's air mix control motor.

    NO  -Go to step 13.

  13. Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector B (16P) terminal No. 5 and body ground.
    Fig 3: Measuring Voltage Between Climate Control Unit Connector Terminal And Body Ground
    G06968322Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there any voltage? 

    YES  -Repair a short to power in the wire(s) between the climate control unit and the passenger's air mix control motor. This short may also damage the climate control unit. Repair a short to power before replacing the climate control unit.

    NO  -Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION  ).

  14. Turn the ignition switch to LOCK (0), and disconnect climate control unit connectors A(28P) and B(16P).
  15. Disconnect these items:
    • Driver's air mix control motor
    • Passenger's air mix control motor
    • Humidity/in-car temperature sensor
    • A/C pressure sensor
  16. Check for continuity between climate control unit connector A (28P) terminal No. 25 and body ground.
    Fig 4: Checking Continuity Between Climate Control Unit Connector Terminal And Body Ground
    G06968323Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short to body ground in the wire.

    NO  -Go to step 17.

  17. Turn the ignition switch to ON (II), and measure the voltage climate control unit connector A (28P) terminal No. 25 and body ground.
    Fig 5: Measuring Voltage Between Terminal And Body Ground
    G06968324Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there any voltage? 

    YES  -Repair a short to power in the wire. This short may have also damaged the climate control unit. Repair a short to power before replacing the climate control unit.

    NO  -Go to step 18.

  18. Turn the ignition switch to LOCK (0).
  19. Reconnect climate control unit connector A (28P).
  20. Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (28P) terminal No. 25 and body ground.
    Fig 6: Measuring Voltage Between Climate Control Unit Connector Terminal And Body Ground
    G06968325Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    YES  -Go to step 21.

    NO  -Check for a loose wire or poor connection at climate control unit connector A (28P). If the connection is good, substitute a known-good climate control unit and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION  ).

  21. While measuring the voltage between the same terminal and body ground, reconnect these items individually and note the voltage reading each time:
    • Driver's air mix control motor
    • Passenger's air mix control motor
    • Humidity/in-car temperature sensor
    • A/C pressure sensor
      Fig 7: Identifying Climate Control Unit Connector A (28P)
      G06968326Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Does the voltage remain at about 5 V? 

    YES  -Substitute a known-good climate control unit and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION  ).

    NO  -Replace the component that caused the voltage drop.

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