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PCM Power and Ground Circuit Troubleshooting

  1. Check the No. A3-2 IG1 MAIN (50 A) fuse in the main under-hood fuse box.

    Is the fuse OK? 

    YES  -Repair an open in the wire between the No. A3-2 IG1 MAIN (50 A) fuse and the ignition switch. If the wire is OK, go to step 2.

    NO  -Repair a short in the wire between the No. A3-2 IG1 MAIN (50 A) fuse and the ignition switch. Also replace the No. A3-2 IG1 MAIN (50 A) fuse.

  2. Inspect the No. B10 Fl MAIN (15 A) fuse in the under-hood fuse/relay box.

    Is the fuse OK? 

    YES  -Go to step  9.

    NO  -Go to step 3.

  3. Remove the blown No. B10 Fl MAIN (15 A) fuse from the under-hood fuse/relay box.
  4. Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.
    Fig 1: Identifying PGM-FI Main Relay
    G06963892Courtesy of AMERICAN HONDA MOTOR CO., INC.
  5. Check for continuity between body ground and PGM-FI main relay 1 4P connector terminals No. 1 and No. 4 individually.
    Fig 2: Checking Continuity Between Body Ground And PGM-FI Main Relay 1 4P Connector Terminals No. 1 And No. 4
    G06963893Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ). Also replace the No. B10 Fl MAIN (15 A) fuse.

    NO  -Go to step 6.

  6. While disconnecting each of the parts or connectors below, one at a time, check for continuity between PGM-FI main relay 1 4P connector terminal No. 2 and body ground:
    • PGM-FI main relay 2
    • PCM connector B (49P)
    • Each injector 2P connector
    • Camshaft position (CMP) sensor 3P connector
    • Crankshaft position (CKP) sensor 3P connector
    • MAF sensor/IAT sensor 5P connector
    • Electronic throttle control system (ETCS) control relay
      Fig 3: Checking Continuity Between PGM-FI Main Relay 1 4P Connector Terminal No. 2 And Body Ground
      G06963894Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Does continuity go away when one of the above parts or connectors is disconnected? 

    YES  -Replace the part that made the short to body ground go away when disconnected. If the part is the PCM, update the PCM if it does not have the latest software (see PCM UPDATE  ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM (see PCM REPLACEMENT  ). Also replace the No. B10 Fl MAIN (15 A) fuse.

    NO  -Go to step 7.

  7. Disconnect the connectors from these parts:
    • PGM-FI main relay 2
    • PCM connector B (49P)
    • Injectors
    • Camshaft position (CMP) sensor
    • Crankshaft position (CKP) sensor
    • MAF sensor/IAT sensor
    • Electronic throttle control system (ETCS) control relay
  8. Check for continuity between PGM-FI main relay 1 4P connector terminal No. 2 and body ground.
    Fig 4: Checking Continuity Between PGM-FI Main Relay 1 4P Connector Terminal No. 2 And Body Ground
    G06963895Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short in the wire between PGM-FI main relay 1 and each part. Also replace the No. B10 Fl MAIN (15 A) fuse.

    NO  -Replace PGM-FI main relay 1. Also replace the No. B10 Fl MAIN (15 A) fuse.

  9. Check the No. C21 FUEL PUMP (20 A) fuse in the driver's under-dash fuse/relay box.

    Is the fuse OK? 

    YES  -Go to step  21.

    NO  -Go to step 10.

  10. Remove the blown No. C21 FUEL PUMP (20 A) fuse from the driver's under-dash fuse/relay box.
  11. Remove PGM-FI main relay 2 (A) from the driver's under-dash fuse/relay box.
    Fig 5: Identifying PGM-FI Main Relay
    G06963896Courtesy of AMERICAN HONDA MOTOR CO., INC.
  12. Test PGM-FI main relay 2 (see POWER RELAY TEST ).

    Is the relay OK? 

    YES  -Go to step 13.

    NO  -Replace PGM-FI main relay 2. Also replace the No. C21 FUEL PUMP (20 A) fuse.

  13. Check for continuity between PGM-FI main relay 2 4P connector terminal No. 1 and body ground.
    Fig 6: Checking Continuity Between PGM-FI Main Relay 2 4P Connector Terminal No. 1 And Body Ground
    G06963897Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 14.

    NO  -Go to step  17.

  14. Jump the SCS line with the HDS.
  15. Disconnect PCM connector B (49P).
  16. Check for continuity between PCM connector terminal B42 and body ground.
    Fig 7: Checking Continuity Between PCM Connector Terminal B42 And Body Ground
    G06963898Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short in the wire between the No. C21 FUEL PUMP (20 A) fuse and the PCM (B42), between the No. C21 FUEL PUMP (20 A) fuse and PGM-FI main relay 2, or between the No. C21 FUEL PUMP (20 A) fuse and the immobilizer control unit. Also replace the No. C21 FUEL PUMP (20 A) fuse.

    NO  -Replace the No. C21 FUEL PUMP (20 A) fuse, and update the PCM if it does not have the latest software (see PCM UPDATE  ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM (see PCM REPLACEMENT  ).

  17. Move the second row seat forward.
  18. Remove the access panel from the floor (see step 3 on FUEL TANK UNIT REMOVAL AND INSTALLATION ).
  19. Disconnect the fuel pump 4P connector.
  20. Check for continuity between fuel pump 4P connector terminal No. 1 and body ground.
    Fig 8: Checking Continuity Between Fuel Pump 4P Connector Terminal No. 1 And Body Ground
    G06963899Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Repair a short in the wire between the fuel pump and PGM-FI main relay 2. Also replace the No. C21 FUEL PUMP(20A)fuse.

    NO  -Check the fuel pump, and replace it if needed (see FUEL FILTER REPLACEMENT ). Also replace the No. C21 FUEL PUMP (20 A) fuse.

  21. Jump the SCS line with the HDS.
  22. Disconnect PCM connectors A (49P) and B (49P).
  23. Turn the ignition switch to ON (II).
  24. Measure the voltage between PCM connector terminal B42 and body ground.
    Fig 9: Measuring Voltage Between PCM Connector Terminal B42 And Body Ground
    G06963900Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step 25.

    NO  -Repair an open in the wire between the No. C21 FUEL PUMP (20 A) fuse and the PCM (B42).

  25. Measure the voltage between PCM connector terminal A6 and body ground.
    Fig 10: Measuring Voltage Between PCM Connector Terminal A6 And Body Ground
    G06963901Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step  30.

    NO  -Go to step 26.

  26. Turn the ignition switch to LOCK (0).
  27. Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.
    Fig 11: Identifying PGM-FI Main Relay
    G06963902Courtesy of AMERICAN HONDA MOTOR CO., INC.
  28. Measure the voltage between PGM-FI main relay 1 4P connector terminal No. 4 and body ground.
    Fig 12: Measuring Voltage Between PGM-FI Main Relay 4P Connector Terminal No. 4 And Body Ground
    G06963903Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step 29.

    NO  -Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ).

  29. Check for continuity between PCM connector terminal A6 and PGM-FI main relay 1 4P connector terminal No. 3.
    Fig 13: Checking Continuity Between PCM Connector Terminal A6 And PGM-FI Main Relay 1 4P Connector Terminal No. 3
    G06963904Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Test PGM-FI main relay 1 (see POWER RELAY TEST ). If the relay is OK, update the PCM if it does not have the latest software (see PCM UPDATE  ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM (see PCM REPLACEMENT  ).

    NO  -Repair an open in the wire between the PCM (A6) and PGM-FI main relay 1.

  30. Turn the ignition switch to LOCK (0).
  31. Remove PGM-FI main relay 1 (A) from the under-hood fuse/relay box.
    Fig 14: Identifying PGM-FI Main Relay
    G06963905Courtesy of AMERICAN HONDA MOTOR CO., INC.
  32. Measure the voltage between PGM-FI main relay 1 4P connector terminal No. 1 and body ground.
    Fig 15: Measuring Voltage Between PGM-FI Main Relay 4P Connector Terminal No. 1 And Body Ground
    G06963906Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step 33.

    NO  -Replace the under-hood fuse/relay box (see REMOVAL AND INSTALLATION ).

  33. Check for continuity between PCM connector terminal B3 and PGM-FI main relay 1 4P connector terminal No. 2.
    Fig 16: Checking Continuity Between PCM Connector Terminal B3 And PGM-FI Main Relay 4P Connector Terminal No. 2
    G06963907Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 34.

    NO  -Repair an open in the wire between the PCM (B3) and PGM-FI main relay 1.1

  34. Test PGM-FI main relay 1 (see POWER RELAY TEST ).

    Is PGM-FI main relay 1 OK? 

    YES  -Go to step 35.

    NO  -Replace PGM-FI main relay 1.1

  35. Disconnect PCM connectors A (49P), B (49P), and C (49P).
  36. Check for continuity between body ground and PCM connector terminals A41, B1, B40, B41, C1, and C41 individually.
    Fig 17: Checking Continuity Between Body Ground And PCM Connector Terminal A (49P)
    G06963908Courtesy of AMERICAN HONDA MOTOR CO., INC.
    Fig 18: Checking Continuity Between Body Ground And PCM Connector Terminal B (49P)
    G06963909Courtesy of AMERICAN HONDA MOTOR CO., INC.
    Fig 19: Checking Continuity Between Body Ground And PCM Connector Terminal C (49P)
    G06963910Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Update the PCM if it does not have the latest software (see PCM UPDATE  ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM (see PCM REPLACEMENT  ).

    NO  -Repair an open in the wire(s) between the PCM (A41, B1, B40, B41, C1, C41) and body ground (G101) (see ENGINE WIRE HARNESS (ENGINE SECTION) (D) ).

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