Malfunction Indicator Lamp: Testing and Inspection
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?
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 61. But if the MIL sometimes works normally, first check for these problems.
- An intermittent short in the wire between the ECM (B17) and the Data Link Connector (DLC).
- An intermittent short in the wire between the ECM (A18) 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.6 (7.5 A) fuse in the under-dash fuse/relay box.
- A loose No.1 (50 A) fuse in the under-hood fuse/relay box.
- A loose No.7 (15 A) fuse in the under-hood fuse/relay box.
- A loose No.2 (15 A) fuse in the under-dash fuse/relay box.
- A poor connection at ECM terminal A18.
- An intermittent open in the GRN/ORN wire between the ECM (A18) and the gauge assembly.
- An intermittent short in the wire between the ECM (C19) and the manifold absolute pressure (MAP) sensor.
- An intermittent short in the wire between the ECM (C28) and the throttle position (TP) sensor, brake booster pressure sensor, fuel tank pressure (FTP) sensor, exhaust gas recirculation (EGR) valve position sensor.
- An intermittent short in the wire between the ECM (B6) and the TCM.
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.6 (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 the No.6 (7.5 A) fuse and the gauge assembly. Also replace the No.6 (7.5 A) fuse.
9. Inspect the No.1 (50 A) fuse in the under-hood fuse/relay box.
Is the fuse OK?
YES - Repair open in the wire between the No.1 (50 A) fuse and the gauge assembly. If the wires are OK, test the ignition switch.
NO - Repair short in the wire between the No.1 (50 A) fuse and the under-dash fuse/relay box. Also replace the No.1 (50 A) 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 ECM connector terminal A18 to body ground with a jumper wire.
13. Turn the ignition switch ON (II).
Is the MIL on?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Check for an open in the wire between the ECM (A18) 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.7 (15 A) 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.7 (15 A) fuse in the under-dash fuse/relay box.
17. Remove the PGM-FI main relay (IGP).
18. Check for continuity between body ground and the PGM-FI main relay (IGP) 4P connector terminal No.2.
Is there continuity?
YES - Repair short in the wire between the No.7 (15 A) fuse and the PGM-FI main relay (IGP). Also replace the No.7 (15 A) fuse.
NO - Go to step 19.
19. Disconnect each of the components or the connectors below, one at a time, and check for continuity between PGM-FI main relay (IGP) 4P connector terminal No.1 and body ground.
- PGM-FI main relay (FUEL PUMP)
- ECM connector B (25P)
- Each injector 2P connector
- Idle air control (IAC) valve 3P 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 ECM, update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
Also replace the No.7 (15 A) fuse.
20. Disconnect the connectors of all these components.
- PGM-FI main relay (FUEL PUMP)
- ECM connector B (25P)
- Injectors
- Idle air control (IAC) valve
21. Check for continuity between PGM-FI main relay (IGP) 4P connector terminal No.2 and body ground.
Is there continuity?
YES - Repair short in the wire between the PGM-FI main relay (IGP) and each item. Also replace the No.7 (15 A) fuse.
NO - Replace the PGM-FI main relay (IGP). Also replace the No.7 (15 A) fuse.
22. Inspect the No.2 (15 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 29.
NO - Go to step 23.
23. Remove the blown No.2 (15 A) fuse in the underdash fuse/relay box.
24. Remove the PGM-FI main relay (FUEL PUMP).
25. Remove the fuel tank.
26. Check for continuity between fuel pump 5P connector terminal No.5 and body ground.
Is there continuity?
YES - Repair short in the wire between the fuel pump and the PGM-FI main relay (FUEL PUMP). Also replace the No.2 (15 A) fuse.
NO - Go to step 27.
27. Reinstall the PGM-FI main relay (FUEL PUMP).
28. Check for continuity between fuel pump 5P connector terminal No.5 and body ground.
Is there continuity?
YES - Replace the PGM-FI main relay (FUEL PUMP). Also replace the No.2 (15 A) fuse.
NO - Check the fuel pump, and replace it if necessary. Also replace the No.2 (15 A) fuse.
29. Check for continuity between body ground and PGM-FI main relay diode 2P connector terminal No.2.
Is there continuity?
YES - Go to step 30.
NO - Repair open in the wire between the PGM-FI main relay and G101.
30. Measure voltage between body ground and ECM connector terminals B1 and B9 individually.
Is there battery voltage?
YES - Go to step 37.
NO - Go to step 31.
31. Turn the ignition switch OFF.
32. Remove the PGM-FI main relay (IGP).
33. Turn the ignition switch ON (II).
34. Measure voltage between PGM-FI main relay (IGP) 4P connector terminal No.2 and body ground.
Is there battery voltage?
YES - Go to step 35.
NO - Repair open in the wire between the No.7 (15 A) fuse and the PGM-FI main relay (IGP).
35. Turn the ignition switch OFF.
36. Check for continuity between PGM-FI main relay (IGP) 4P connector terminal No.1 and ECM connector terminals B1 and B9 individually.
Is there continuity?
YES - Replace the PGM-FI main relay (IGP).
NO - Repair open in the wire between the PGM-FI main relay (IGP) and the ECM (B1, B9).
37. Measure voltage between body ground and ECM connector terminals B2, B10, B20 and B22 individually.
Is there more than 1.0 V?
YES - Repair open in the wire(s) that had more than 1.0 V between G101 and the ECM (B2, B10, B20, B22).
NO - Go to step 38.
38. Measure voltage between body ground and ECM connector terminal C19.
Is there about 5 V?
YES - Go to step 46.
NO - Go to step 39.
39. Turn the ignition switch OFF.
40. Disconnect the manifold absolute pressure (MAP) sensor 3P connector.
41. Turn the ignition switch ON (II).
42. Measure voltage between body ground and ECM connector terminal C19.
Is there about 5 V?
YES - Replace the MAP sensor.
NO - Go to step 43.
43. Turn the ignition switch OFF.
44. Disconnect ECM connector C (31P).
45. Check for continuity between ECM connector terminal C19 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (C19) and the MAP sensor.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
46. Measure voltage between body ground and ECM connector terminal C28.
Is there about 5 V?
YES -
- Go to step 53. (CVT model)
- Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. (M/T model)
NO - Go to step 47.
47. Turn the ignition switch OFF.
48. Disconnect the 3P connector from each of these sensors, one at a time, and measure voltage between body ground and ECM connector terminal C28 with the ignition switch ON (II).
- Exhaust gas recirculation (EGR) valve position sensor
- Brake booster pressure sensor
- Fuel tank pressure (FTP) sensor
- Throttle position (TP) sensor
Is there about 5 V?
YES - Replace the sensor that restored about 5 V when disconnected.
NO - Go to step 49.
49. Turn the ignition switch OFF.
50. Disconnect the 3P connectors from the following sensors.
- Exhaust gas recirculation (EGR) valve position sensor
- Brake booster pressure sensor
- Fuel tank pressure (FTP) sensor
- Throttle position (TP) sensor
51. Disconnect ECM connector C (31P).
52. Check for continuity between ECM connector terminal C28 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (C28) and the EGR valve position sensor, brake booster pressure sensor, FTP sensor, or TP sensor.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
53. Measure voltage between body ground and ECM connector terminal B6.
Is there about 5 V?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Go to step 54.
54. Turn the ignition switch OFF.
55. Disconnect the TCM 22P connector.
56. Turn the ignition switch ON (II).
57. Measure voltage between body ground and ECM connector terminal B6.
Is there about 5 V?
YES - Substitute a known-good TCM and recheck. If the symptom/indication goes away, replace the original TCM.
NO - Go to step 58.
58. Turn the ignition switch OFF.
59. Disconnect ECM connector B (25P).
60. Check for continuity between ECM connector terminal B6 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (B6) and the TCM.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
61. Measure voltage between ECM connector terminal B17 and body ground.
Is there about 5 V (or battery voltage)?
YES - Go to step 65.
NO - Go to step 62.
62. Turn the ignition switch OFF.
63. Disconnect ECM connector B (25P).
64. Check for continuity between ECM connector terminal B17 and body ground.
Is there continuity?
YES - Repair short in the wire between the DLC and the ECM (B17).
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
65. Turn the ignition switch OFF.
66. Disconnect ECM connector B (25P).
67. Turn the ignition switch ON (II).
Is the MIL on?
YES - Repair short in the wire between the gauge assembly and the ECM (B17). If the wires are OK, replace the gauge assembly.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.