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DTC B12C5: Engine Start/Stop Switch Failure

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 ).
  1. Clear the DTCs with the HDS.
  2. Press the engine start/stop button at least 20 times, then wait for at least 20 seconds.
  3. Check for DTCs with the HDS.

    Is DTC B12C5 indicated? 

    YES  - Go to step 4.

    NO  - Intermittent failure, the system is OK at this time. Check for loose or poor connections.

  4. Do the engine start/stop switch test (see ENGINE START/STOP SWITCH TEST/REPLACEMENT ).

    Is the engine start/stop switch OK? 

    YES  - Go to step 5.

    NO  - Replace the engine start/stop switch (see ENGINE START/STOP SWITCH TEST/REPLACEMENT  ).

  5. Reconnect the engine start/stop switch 10P connector.
  6. Measure the voltage between body ground and engine start/stop switch 10P connector terminal No. 1.
    Fig 1: Measuring Voltage Between Body Ground And Engine Start/Stop Switch 10P Connector Terminal No. 1 With Connector End View
    G08067645Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  - Go to step 7.

    NO  - Check the No. 12 (10 A) fuse in the passenger's under- dash fuse/relay box. If the fuse is OK, check for an open in the wire.

  7. Press and hold the engine start/stop button.
  8. Measure the voltage between body ground and engine start/stop switch 10P connector terminal No. 4.
    Fig 2: Measuring Voltage Between Body Ground And Engine Start/Stop Switch 10P Connector Terminal No. 4
    G08067646Courtesy 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 wire or poor ground (G405).

  9. Disconnect the engine start/stop switch 10P connector.
  10. Disconnect power control unit connector C (36P).
  11. Check for continuity between engine start/stop switch 10P connector terminals No. 2 and No. 5, and power control unit connector C (36P) terminals No. 8 and No. 7 respectively.
    Fig 3: Checking Continuity Between Engine Start/Stop Switch 10P Connector Terminals And Power Control Unit Connector C (36P) Terminals With Connector End View
    G08067647Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Replace the power control unit (see CONTROL UNIT INPUT TEST  ).

    NO  - Repair an open or high resistance in the wire.

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