MIL Circuit Troubleshooting
MIL Circuit Troubleshooting1. Connect an OBD II scan tool/Honda PGM Tester.
2. 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?
YES - Go to step 3.
NO - Go to troubleshooting "DLC Circuit Troubleshooting".
3. Check the OBD II scan tool/Honda PGM Tester for DTCs.
Are any DTCs indicated?
YES - Go to the DTC Troubleshooting Index. Diagnostic Trouble Code Descriptions
NO - Go to step 4.
4. Turn the ignition switch OFF.
5. 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)?
YES - If the MIL always comes on and stays on, go to step 76. But if the MIL sometimes works normally, first check for these problems.
- An intermittent short in the wire between the PCM (E29) and the data link connector (DLC).
- An intermittent short in the wire between the PCM (E31) and the gauge assembly.
NO - If the MIL is always off, go to step 6. 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 (PCM) (15A) fuse in the underhood fuse/relay box.
- A loose No.17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.
- A poor connection at PCM terminal E31.
- An intermittent open in the GRN/ORN wire between the PCM (E31) and the gauge assembly.
- An intermittent short in the wire between the PCM (A21) and the manifold absolute pressure (MAP) sensor, CVT driven pulley speed sensor, CVT speed sensor, or fuel pressure sensor.
- An intermittent short in the wire between the PCM (A20) and the throttle position (TP) sensor, CVT drive pulley speed sensor, or CVT speed sensor 2.
- An intermittent short in the wire between the PCM (E5) and the fuel tank pressure (FTP) sensor.
6. Turn the ignition switch OFF.
7. Turn the ignition switch ON (II).
Is the low oil pressure light on?
YES - Go to step 10.
NO - Go to step 8.
8. Inspect the No.10 METER (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 9.
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.
9. Inspect the No.20 IG1 (40A) fuse in the under-hood fuse/relay box.
Is the fuse OK?
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.
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.
10. Try to start the engine.
Does the engine start?
YES - Go to step 11.
NO - Go to step 14.
11. Turn the ignition switch OFF.
12. Connect PCM connector terminal E31 to body ground with a jumper wire.
13. Turn the ignition switch ON (II).
Is the MIL on?
YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Check for an open in the wire between the 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.
14. Turn the ignition switch OFF.
15. Inspect the No.6 ECU (PCM) (15A) fuse in the under-hood fuse/relay box.
Is the fuse OK?
YES - Go to step 22.
NO - Go to step 16.
16. Remove the blown No.6 ECU (PCM) (15A) fuse in the under-dash fuse/relay box.
17. Remove the glove box, then remove PGM-FI main relay 1 (A) and the injector relay (B).
18. Check for continuity between body ground and PGM-FI main relay 1 4P connector terminals No.2 and No.4 individually.
Is there continuity?
YES - Repair short in the wire between the No.6 ECU (PCM) (15A) fuse and the PGM-FI main relay 1/injector relay. Also replace the No.6 ECU (PCM) (15A) fuse.
NO - Go to step 19.
19. Disconnect each of the component or the connector sensors below, one at a time, and check for continuity between PGM-FI main relay 1 4P connector terminal No.1 and body ground.
- PGM-FI main relay 2
- PCM connector A (31P)
- Each injector 2P connector
- Idle air control (IAC) valve 3P connector
- Camshaft speed (CMP) sensor (Top dead center (TDC) sensor) 3P connector
- Crankshaft position (CKP) sensor 3P connector
- Injector relay 4P connector
- Injector control module 26P connector
Is there continuity?
YES - Go to step 20.
NO - Replace the component that made continuity to body ground go away when disconnected. If the item is the PCM, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
Also replace the No.6 ECU (PCM) (15A) fuse.
20. Disconnect the connectors of all these components.
- PGM-FI main relay 2
- PCM connector A (31P)
- Injectors
- Idle air control (IAC) valve
- Camshaft speed (CMP) sensor (Top dead center (TDC) sensor)
- Crankshaft position (CKP) sensor
- Injector relay
- Injector control module
21. Check for continuity between PGM-FI main relay 1 4P connector terminal No.1 and body ground.
Is there continuity?
YES - Repair short in the wire between PGM-FI main relay 1 and each item. Also replace the No.6 ECU (PCM) (15A) fuse.
NO - Replace the PGM-FI main relay 1. Also replace the No.6 ECU (PCM) (15A) fuse.
22. Inspect the No.17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 35.
NO - Go to step 23.
23. Remove the blown No.17 FUEL PUMP (15A) fuse in the under-dash fuse/relay box.
24. Disconnect PCM connector E (31P).
25. Check for continuity between PCM connector terminal E9 and body ground.
Is there continuity?
YES - Go to step 26.
NO - Replace the No.17 FUEL PUMP (15A) fuse, and update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
26. Remove the glove box, then remove PGM-FI main relay 2 (A).
27. Check for continuity between PCM connector terminal E9 and body ground.
Is there continuity?
YES - Repair short in the wire between the No.17 FUEL PUMP (15A) fuse and the PCM (E9), or the No.17 FUEL PUMP (15A) fuse and PGM-FI main relay 2. Also replace the No.17 FUEL PUMP (15A) fuse.
NO - Go to step 28.
28. Remove the rear seat cushion.
29. Disconnect the fuel subharness 6P connector.
30. Disconnect the fuel pressure regulator shut-off solenoid valve 2P connector.
31. Check for continuity between fuel pressure regulator shut-off solenoid valve 2P connector terminal No.2 and body ground.
Is there continuity?
YES - Repair short in the wire between the fuel pressure regulator shut-off solenoid valve and PGM-FI main relay 2. Also replace the No.17 FUEL PUMP (15A) fuse.
NO - Go to step 32.
32. Check for continuity between fuel subharness 6P connector terminal No.2 and body ground.
Is there continuity?
YES - Repair short in the wire between the fuel sub-harness 6P connector and PGM-FI main relay 2. Also replace the No.17 FUEL PUMP (15A) fuse.
NO - Go to step 33.
33. Reinstall PGM-FI main relay 2 (A).
34. Check for continuity between fuel pressure regulator shut-off solenoid valve 2P connector terminal No.2 and body ground.
Is there continuity?
YES - Replace PGM-FI main relay 2. Also replace the No.17 FUEL PUMP (15A) fuse.
NO - Check the fuel pressure regulator shut-off solenoid valve, fuel tank internal solenoid valve and fuel subharness, and replace them as necessary. Also replace the No.17 FUEL PUMP (15A) fuse.
35. Disconnect PCM connector E (31P).
36. Turn the ignition switch ON (II).
37. Measure voltage between PCM connector terminals E9 and body ground.
Is there battery voltage?
YES - Go to step 38.
NO - Repair open in the wire between the No.17 FUEL PUMP (15A) fuse and the PCM (E9).
38. Measure voltage between PCM connector terminal E7 and body ground.
Is there battery voltage?
YES - Go to step 43.
NO - Go to step 39.
39. Turn the ignition switch OFF.
40. Remove PGM-FI main relay 1(A).
41. Measure voltage between PGM-FI main relay 1 4P connector terminal No.4 and body ground.
Is there battery voltage?
YES - Go to step 42.
NO - Repair open in the wire between No.6 ECU (PCM) (15A) fuse and the PGM-FI main relay 1.
42. Check for continuity between PGM-FI main relay 1 4P connector terminal No.3 and PCM connector terminal E7.
Is there continuity?
YES - Test PGM-FI main relay 1. If the relay is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Repair open in the wire between PGM-FI main relay 1 and the PCM (E7).
43. Turn the ignition switch OFF.
44. Reconnect PCM connector E (31P).
45. Turn the ignition switch ON (II).
46. Measure voltage between body ground and PCM connector terminals A2 and A3 individually.
Is there battery voltage?
YES - Go to step 53.
NO - Go to step 47.
47. Turn the ignition switch OFF.
48. Remove PGM-FI main relay 1(A).
49. Turn the ignition switch ON (II).
50. Measure voltage between PGM-FI main relay 1 4P connector terminal No.2 and body ground.
Is there battery voltage?
YES - Go to step 51.
NO - Repair open in the wire between the No.6 ECU (PCM) (15A) fuse and the PGM-FI main relay 1.
51. Turn the ignition switch OFF.
52. Check for continuity between PGM-FI main relay 1 4P connector terminal No.1 and PCM connector terminals A2 and A3 individually.
Is there continuity?
YES - Replace PGM-FI main relay 1.
NO - Repair open in the wire between PGM-FI main relay 1 and the PCM (A2,A3).
53. Measure voltage between body ground and PCM connector terminals A4, A5, A23, and A24 individually.
Is there less than 1.0 V?
YES - Repair open in the wire(s) that had more than 1.0 V between G101 and the PCM (A4, A5, A23, A24).
NO - Go to step 54.
54. Measure voltage between body ground and PCM connector terminal A21.
Is there about 5 V?
YES - Go to step 61.
NO - Go to step 55.
55. Turn the ignition switch OFF.
56. Disconnect the 3P connector from each of these sensors, one at a time, and measure voltage between body ground and PCM connector terminal A21 with the ignition switch ON (II).
- Manifold absolute pressure (MAP) sensor
- CVT driven pulley speed sensor
- CVT speed sensor 1
- fuel pressure sensor
Is there about 5 V?
YES - Replace the sensor that restored 5 V when disconnected.
NO - Go to step 57.
57. Turn the ignition switch OFF.
58. Disconnect 3P connector from the following sensors.
- Manifold absolute pressure (MAP) sensor
- CVT driven pulley speed sensor
- CVT speed sensor 1
- fuel pressure sensor
59. Disconnect PCM connector A (31P).
60. Check for continuity between PCM connector terminal A21 and body ground.
Is there continuity?
YES - Repair short in the wire between the PCM (A21) and the MAP sensor, CVT driven pulley speed sensor, CVT speed sensor, or fuel pressure sensor.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
61. Measure voltage between body ground and PCM connector terminal A20.
Is there about 5 V?
YES - Go to step 68.
NO - Go to step 62.
62. Turn the ignition switch OFF.
63. Disconnect the 3P connector from each of these sensors, one at a time, and measure voltage between body ground and PCM connector terminal A20 with the ignition switch ON (II).
- Throttle position (TP) sensor
- CVT drive pulley speed sensor
- CVT speed sensor 2
Is there about 5 V?
YES - Replace the sensor that restored about 5 V when disconnected.
NO - Go to step 64.
64. Turn the ignition switch OFF.
65. Disconnect the 3P connectors from the following sensors.
- Throttle position (TP) sensor
- CVT drive pulley speed sensor
- CVT speed sensor 2
66. Disconnect PCM connector A (31P)
67. Check for continuity between PCM connector terminal A20 and body ground.
Is there continuity?
YES - Repair short in the wire between the PCM (A20) and the TP sensor, CVT drive pulley speed sensor, CVT speed sensor 2, or repair short in the wire between the PCM (A8) and the knock sensor.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
68. Measure voltage between body ground and PCM connector terminal E5.
Is there about 5 V?
YES - Update the PCM if it does not have the latest software or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Go to step 69.
69. Turn the ignition switch OFF.
70. Disconnect the fuel tank pressure (FTP) sensor 3P connector.
71. Turn the ignition switch ON (II).
72. Measure voltage between body ground and PCM connector terminal E5.
Is there about 5 V?
YES - Replace the FTP sensor.
NO - Go to step 73.
73. Turn the ignition switch OFF.
74. Disconnect PCM connector E (31P).
75. Check for continuity between PCM connector terminal F5 and body ground.
Is there continuity?
YES - Repair short in the wire between the PCM (E5) and the FTP sensor.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
76. Watch the low fuel indicator light. Does the low fuel indicator light blink?
YES - Check the low fuel indicator light
NO - Go to step 77.
77. Turn the ignition switch OFF.
78. Turn the ignition switch ON (II).
79. Measure voltage between PCM connector terminal E29 and body ground.
Is there about 5 V (or battery voltage)?
YES - Go to step 83.
NO - Go to step 80.
80. Turn the ignition switch OFF.
81. Disconnect PCM connector E (31P).
82. Check for continuity between PCM connector terminal E29 and body ground.
Is there continuity?
YES - Repair short in the wire between the DLC and the PCM (E29).
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
83. Turn the ignition switch OFF.
84. Disconnect PCM connector E (31P).
85. Turn the ignition switch ON (II).
Does MIL stay on?
YES - Repair short in the wire between the gauge assembly and the PCM (E31). If the wires are OK, replace the gauge assembly.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.