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MIL Circuit Troubleshooting

  1. Turn the ignition switch ON (II) and watch the Malfunction Indicator Lamp (MIL).

    Does the MIL come on and stay on for more than 20 seconds after turning the ignition switch ON (II)? 

    1. YES  - If the MIL always comes on and stays on, go to  71. But if the MIL sometimes works normally, first check for these problems.
      • An intermittent short in the wire between the ECM PCM (E29) and the Data Link Connector (DLC).
      • An intermittent short in the wire between the ECM PCM (E31) and the gauge assembly.
    2. NO  - If the MIL is always off, go to step 2. But if the MIL sometimes works normally, first check for these problems.
      • A loose No. 10 METER (7.5A) fuse in the under-dash fuse/relay box.
      • A loose No. 20 IG (40A) fuse in the under-hood fuse/relay box.
      • A loose No. 6 ECU (ECM/PCM) (15A) fuse in the under-hood fuse/relay box.
      • A loose No. 17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.
      • A poor connection at ECM/PCM terminal E31.
      • An intermittent open in the GRN/ORN wire between the ECM/PCM (E31) and the gauge assembly.
      • An intermittent short in the wire between the ECM PCM (A21) and the manifold absolute pressure (MAP) sensor.
      • An intermittent short in the wire between the ECM PCM (A20) and the throttle position (TP) sensor, knock sensor, exhaust gas recirculation (EGR) valve position sensor.
      • An intermittent short in the wire between the ECM PCM (A8) and the knock sensor.
      • An intermittent short in the wire between the ECM PCM (E5) and the fuel tank pressure (FTP) sensor.
  2. Turn the ignition switch OFF.
  3. Turn the ignition switch ON (II).

    Is the low oil pressure light on? 

    1. YES  - Go to step  6.
    2. NO  - Go to step 4.
  4. Inspect the No. 10 METER (7.5 A) fuse in the under-dash fuse/relay box.

    Is the fuse OK? 

    1. YES  - Go to step 5.
    2. NO  - Repair short in the wire between No. 10 METER (7.5A) fuse and the gauge assembly. Also replace the No. 10 METER (7.5A) fuse.
  5. Inspect the No. 20 IG1 (40A) fuse in the under-hood fuse/relay box.

    Is the fuse OK? 

    1. YES  - Repair open in the wire between the No. 20 IG (40A) fuse and the gauge assembly. If the wires are OK, test the ignition switch (seeTEST ).
    2. NO  - Repair short in the wire between No. 20 IG (40A) fuse and the under-dash fuse/relay box. Also replace the No. 20 IG (40A) fuse.
  6. Try to start the engine.

    Does the engine start? 

    1. YES  - Go to step 7.
    2. NO  - Go to step  10.
  7. Turn the ignition switch OFF.
  8. Connect ECM/PCM connector terminal E31 and body ground with a jumper wire.
    Fig 1: Connecting ECM/PCM Connector Terminal E31 & Body Ground
    G01954802
  9. Turn the ignition switch ON (II).

    Is the MIL on? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Check for an open in the wire between the ECM/PCM (E31) and the gauge assembly. Also check for a blown MIL bulb. If the wires and the bulb are OK, replace the gauge assembly.
  10. Turn the ignition switch OFF.
  11. Inspect the No. 6 ECU (ECM/PCM) (15A) fuse in the under-hood fuse/relay box.

    Is the fuse OK? 

    1. YES  - Go to step  18.
    2. NO  - Go to step 12.
  12. Remove the blown No. 6 ECU (ECM/PCM) (15A) fuse in the under-dash fuse/relay box.
  13. Remove the PGM-FI main relay 1.
    Fig 2: Removing PGM-FI Main Relay 1
    G01954803
  14. Check for continuity between body ground and the PGM-FI main relay 1 4P connector terminals No. 2 and No. 4 individually.
    Fig 3: Checking Continuity Between Body Ground & PGM-FI Main Relay 1 4-Pin Connector Terminals No. 2 & No. 4
    G01954804

    Is there continuity? 

    1. YES  - Repair short in the wire between the No. 6 ECU (ECM/PCM) (15A) fuse and the PGM-FI main relay 1. Also replace the No. 6 ECU (ECM/PCM) (15A) fuse.
    2. NO  - Go to step 15.
  15. Disconnect each of the components or the connectors below, one at a time, and check for continuity between the PGM-FI main relay 1 4P connector terminal No. 1 and body ground.
    • PGM-FI main relay 2
    • ECM/PCM connector A (31P)
    • Each injector 2P connector
    • Idle air control (IAC) valve 3P connector
    • Top dead center (TDC) sensor 3P connector
    • Crankshaft position (CKP) sensor 3P connector
    Fig 4: Checking Continuity Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 1 & Body Ground
    G01954805

    Is there continuity? 

    1. YES  - Go to step 16.
    2. NO  - Replace the component that made continuity to body ground go away when disconnected. If the item is the ECM/PCM, reprogram the ECM/PCM if it does not have the latest software, or substitute a known good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known good ECM/PCM, replace the original ECM/PCM.

      Also replace the No. 6 ECU (ECM/PCM) (15 A) fuse.

  16. Disconnect the connectors of all these components.
    • PGM FI main relay 2
    • ECM PCM connector A (31P)
    • Injectors
    • Idle air control (IAC) valve
    • Top dead center (TDC) sensor
    • Crankshaft position (CKP) sensor
  17. Check for continuity between the PGM-FI main relay 1 4P connector terminal No. 2 and body ground.
    Fig 5: Checking Continuity Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 2 & Body Ground
    G01954806

    Is there continuity? 

    1. YES  - Repair short in the wire between the PGM-FI main relay 1 and each item. Also replace the No. 6 ECU (ECM/PCM) (15A) fuse.
    2. NO  - Replace the PGM-FI main relay 1. Also replace the No. 6 ECU (ECM/PCM) (15A) fuse.
  18. Inspect the No. 17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.

    Is the fuse OK? 

    1. YES  - Go to  30.
    2. NO  - Go to step 19.
  19. Remove the blown No. 17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.
  20. Disconnect ECM/PCM connector E (31P).
  21. Check for continuity between ECM/PCM connector terminal E9 and body ground.
    Fig 6: Checking Continuity Between ECM/PCM Connector Terminal E9 & Body Ground
    G01954807

    Is there continuity? 

    1. YES  - Go to step 22.
    2. NO  -Replace the No. 17 FUEL PUMP (15 A) fuse, and reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  22. Remove the PGM-FI main relay 2.
    Fig 7: Removing PGM-FI Main Relay 2
    G01954808
  23. Check for continuity between ECM/PCM connector terminal E9 and body ground.
    Fig 8: Checking Continuity Between ECM/PCM Connector Terminal E9 & Body Ground
    G01954809

    Is there continuity? 

    1. YES  - Repair short in the wire between the No. 17 FUEL PUMP (15A) fuse and the ECM/PCM (E9), or the No. 17 FUEL PUMP (15 A) fuse and the PGM-FI main relay 2. Also replace the No. 17 FUEL PUMP (15A) fuse.
    2. NO  - Go to step 24.
  24. Remove the rear seat cushion.
  25. Remove the access panel from the floor.
  26. Disconnect the fuel pump 5P connector.
  27. Check for continuity between the fuel pump 5P connector terminal No. 5 and body ground.
    Fig 9: Checking Continuity Between Fuel Pump 5-Pin Connector Terminal No. 5 & Body Ground
    G01954810

    Is there continuity? 

    1. YES  - Repair short in the wire between the fuel pump and the PGM-FI main relay 2. Also replace the No. 17 FUEL PUMP (15A) fuse.
    2. NO  - Go to step 28.
  28. Reinstall the PGM-FI main relay 2.
    Fig 10: Reinstalling PGM-FI Main Relay 2
    G01954811
  29. Check for continuity between the fuel pump 5P connector terminal No. 5 and body ground.
    Fig 11: Checking Continuity Between Fuel Pump 5-Pin Connector Terminal No. 5 & Body Ground
    G01954812

    Is there continuity? 

    1. YES  - Replace the PGM-FI main relay 2. Also replace the No. 17 FUEL PUMP (15A) fuse.
    2. NO  - Check the fuel pump, and replace it as necessary. Also replace the No. 17 FUEL PUMP (15A) fuse.
  30. Disconnect ECM/PCM connector E (31P).
  31. Turn the ignition switch ON (II).
  32. Measure voltage between ECM/PCM connector terminals E9 and body ground.
    Fig 12: Measuring Voltage Between ECM/PCM Connector Terminals E9 & Body Ground
    G01954813

    Is there battery voltage? 

    1. YES  - Go to step 33.
    2. NO  - Repair open in the wire between the No. 17 FUEL PUMP (15A) fuse and the ECM/PCM (E9).
  33. Turn the ignition switch OFF.
  34. Measure voltage between ECM/PCM connector terminal E7 and body ground.
    Fig 13: Measuring Voltage Between ECM/PCM Connector Terminal E7 & Body Ground
    G01954814

    Is there battery voltage? 

    1. YES  - Go to step  38.
    2. NO  - Go to step 35.
  35. Remove the PGM-FI main relay 1.
    Fig 14: Removing PGM-FI Main Relay 1
    G01954815
  36. Measure voltage between the PGM-FI main relay 1 4P connector terminal No. 4 and body ground.
    Fig 15: Measuring Voltage Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 4 & Body Ground
    G01954816

    Is there battery voltage? 

    1. YES  - Go to step 37.
    2. NO  - Repair open in the wire between the No. 6 ECU (ECM/PCM) (15 A) fuse and the PGM-FI main relay 1.
  37. Check for continuity between the PGM-FI main relay 1 4P connector terminal No. 3 and ECM/PCM connector terminal E7.
    Fig 16: Checking Continuity Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 3 & ECM/PCM Connector Terminal E7
    G01954817

    Is there continuity? 

    1. YES  - Test the PGM-FI main relay 1 (see RELAYS ). If the relay is OK, reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Repair open in the wire between the PGM-FI main relay 1 and the ECM/PCM (E7).
  38. Reconnect ECM/PCM connector E (31P).
  39. Turn the ignition switch ON (II).
  40. Measure voltage between body ground and ECM/PCM connector terminals A2 and A3 individually.
    Fig 17: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminals A2 & A3
    G01954818

    Is there battery voltage? 

    1. YES  - Go to step  47.
    2. NO  - Go to step 41.
  41. Turn the ignition switch OFF.
  42. Remove the PGM-FI main relay 1.
    Fig 18: Removing PGM-FI Main Relay 1
    G01954819
  43. Turn the ignition switch ON (II).
  44. Measure voltage between the PGM-FI main relay 1 4P connector terminal No. 2 and body ground.
    Fig 19: Measuring Voltage Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 2 & Body Ground
    G01954820

    Is there battery voltage? 

    1. YES  - Go to step 45.
    2. NO  - Repair open in the wire between the No. 6 ECU (ECM/PCM) (15A) fuse and the PGM-FI main relay 1.
  45. Turn the ignition switch OFF.
  46. Check for continuity between the PGM-FI main relay 1 4P connector terminal No. 1 and ECM/PCM connector terminals A2 and A3 individually.
    Fig 20: Checking Continuity Between PGM-FI Main Relay 1 4-Pin Connector Terminal No. 1 & ECM/PCM Connector Terminals A2 & A3
    G01954821

    Is there continuity? 

    1. YES  - Replace the PGM-FI main relay 1.
    2. NO  - Repair open in the wire between the PGM-FI main relay 1 and the ECM/PCM (A2, A3).
  47. Measure voltage between body ground and ECM/PCM connector terminals A4, A5, A23 and A24 individually.
    Fig 21: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminals A4, A5, A23 & A24
    G01954822

    Is there less than 1.0 V? 

    1. YES  - Repair open in the wire(s) that had more than 1.0 V between G101 and the ECM/PCM (A4, A5, A23, A24).
    2. NO  - Go to step 48.
  48. Measure voltage between body ground and ECM/PCM connector terminal A21.
    Fig 22: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal A21
    G01954823

    Is there about 5 V? 

    1. YES  - Go to step  56.
    2. NO  - Go to step 49.
  49. Turn the ignition switch OFF.
  50. Disconnect the manifold absolute pressure (MAP) sensor 3P connector.
  51. Turn the ignition switch ON (II).
  52. Measure voltage between body ground and ECM/PCM connector terminal A21.
    Fig 23: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal A21
    G01954824

    Is there about 5 V? 

    1. YES  - Replace the MAP sensor.
    2. NO  - Go to step 53.
  53. Turn the ignition switch OFF.
  54. Disconnect ECM/PCM connector A (31P).
  55. Check for continuity between ECM/PCM connector terminal A21 and body ground.
    Fig 24: Checking Continuity Between ECM/PCM Connector Terminal A21 & Body Ground
    G01954825

    Is there continuity? 

    1. YES  - Repair short in the wire between the ECM/PCM (A21) and the MAP sensor.
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  56. Measure voltage between body ground and ECM/PCM connector terminal A20.
    Fig 25: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal A20
    G01954826

    Is there about 5 V? 

    1. YES  - Go to step  63.
    2. NO  - Go to step 57.
  57. Turn the ignition switch OFF.
  58. Disconnect the 3P connector from each of these sensors, one at a time, and measure voltage between body ground and ECM/PCM connector terminal A20 with the ignition switch ON (II).
    • Exhaust gas recirculation (EGR) valve position sensor
    • Knock sensor
    • Throttle position (TP) sensor
    Fig 26: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal A20
    G01954827

    Is there about 5 V? 

    1. YES  - Replace the sensor that restored about 5 V when disconnected.
    2. NO  - Go to step 59.
  59. Turn the ignition switch OFF.
  60. Disconnect the 3P connectors from the following sensors.
    • Exhaust gas recirculation (EGR) valve position sensor
    • Knock sensor
    • Throttle position (TP) sensor
  61. Disconnect ECM/PCM connector A (31P).
  62. Check for continuity between ECM/PCM connector terminal A20 and body ground.
    Fig 27: Checking Continuity Between ECM/PCM Connector Terminal A20 & Body Ground
    G01954828

    Is there continuity? 

    1. YES  - Repair short in the wire between the ECM/PCM (A20) and the EGR valve position sensor, knock sensor or TP sensor, or repair short in the wire between the ECM/PCM (A8) and the knock sensor.
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  63. Measure voltage between body ground and ECM/PCM connector terminal E5.
    Fig 28: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal E5
    G01954829

    Is there about 5 V? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Go to step 64.
  64. Turn the ignition switch OFF.
  65. Disconnect the fuel tank pressure (FTP) sensor 3P connector.
  66. Turn the ignition switch ON (II).
  67. Measure voltage between body ground and ECM/PCM connector terminal E5.
    Fig 29: Measuring Voltage Between Body Ground & ECM/PCM Connector Terminal E5
    G01954830

    Is there about 5 V? 

    1. YES  - Replace the FTP sensor.
    2. NO  - Go to step 68.
  68. Turn the ignition switch OFF.
  69. Disconnect ECM/PCM connector E (31P).
  70. Check for continuity between ECM/PCM connector terminal E5 and body ground.
    Fig 30: Checking Continuity Between ECM/PCM Connector Terminal E5 & Body Ground
    G01954831

    Is there continuity? 

    1. YES  - Repair short in the wire between the ECM/PCM (E5) and the FTP sensor.
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  71. Turn the ignition switch OFF.
  72. Connect an OBD II scan tool/Honda PGM Tester (see HOW TO USE THE PGM TESTER OR A SCAN TOOL ).
  73. Turn the ignition switch ON (II), and read the OBD II scan tool/Honda PGM Tester.

    Does the OBD II scan tool/Honda PGM Tester communicate with the ECM/PCM? 

    1. YES  - Go to step  78.
    2. NO  - Go to step 74.
  74. Turn the ignition switch OFF.
  75. Disconnect ECM/PCM connector E (31P).
  76. Check for continuity between body ground and data link connector (DLC) terminal No. 7.
    Fig 31: Checking Continuity Between Body Ground & Data Link Connector (DLC) Terminal No. 7
    G01954832

    Is there continuity? 

    1. YES  - Repair short in the wire between the DLC and the ECM/PCM (E23). After repairing it, check the DTC with the OBD II scan tool/Honda PGM Tester and go to the DTC Troubleshooting Index.
    2. NO  - Go to step 77.
  77. Check for continuity between ECM/PCM connector terminal E23 and DLC terminal No. 7.
    Fig 32: Checking Continuity Between ECM/PCM Connector Terminal E23 & DLC Terminal No. 7
    G01954833

    Is there continuity? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Repair open in the wire between the DLC and the ECM/PCM (E23). After repairing it, check the DTC with the OBD II scan tool/Honda PGM Tester and go to the DTC Troubleshooting Index.
  78. Check the OBD II scan tool/Honda PGM Tester for DTCs.

    Are any DTCs indicated? 

    1. YES  - Go to the DTC Troubleshooting Index.
    2. NO  - Go to step 79.
  79. Turn the ignition switch OFF.
  80. Turn the ignition switch ON (II).
  81. Measure voltage between ECM/PCM connector terminal E29 and body ground.
    Fig 33: Measuring Voltage Between ECM/PCM Connector Terminal E29 & Body Ground
    G01954834

    Is there about 5 V (or battery voltage)? 

    1. YES  - Go to step  85.
    2. NO  - Go to step 82.
  82. Turn the ignition switch OFF.
  83. Disconnect ECM/PCM connector E (31P).
  84. Check for continuity between ECM/PCM connector terminal E29 and body ground.
    Fig 34: Checking Continuity Between ECM/PCM Connector Terminal E29 & Body Ground
    G01954835

    Is there continuity? 

    1. YES  - Repair short in the wire between the DLC and the ECM/PCM (E29).
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  85. Turn the ignition switch OFF.
  86. Disconnect ECM/PCM connector E (31P).
  87. Turn the ignition switch ON (II).

    Is the MIL on? 

    1. YES  - Repair short in the wire between the gauge assembly and the ECM/PCM (E31). If the wires are OK, replace the gauge assembly.
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
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