MIL Circuit Troubleshooting

1.Connect a scan tool/Honda PGM Tester.

2.Turn the ignition switch ON (II) and read the scan tool/Honda PGM Tester.

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


YES - Go to 3.


NO - Go to troubleshooting ‘‘DLC circuit''.


3.Check the scan tool/Honda PGM Tester for DTCs.

Are any DTCs indicated?


YES - Go to the DTC Troubleshooting Index.


NO - Go to 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?


YES - If the MIL always come on and stays on, go to 68. 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) (or the service check connector).
  • An intermittent short in the wire between the ECM/PCM (E31) and the gauge assembly.

NO - If the MIL is always off, go to 6. But if the MIL sometimes works normally, first check for these problems.

  • A loose No. 16 (7.5A) fuse in the under-dash fuse/relay box.
  • A loose No. 3 (50A) fuse in the under-hood fuse/relay box.
  • A loose No. 20 (15A) fuse in the under-dash fuse/relay box.
  • A loose No. 11 (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, CVT driven pulley speed sensor (CVT), CVT speed sensor (CVT).
  • An intermittent short in the wire between the ECM/PCM (A20) and the throttle position (TP) sensor, EGR valve position sensor, CVT drive pully speed sensor (CVT).

6.Turn the ignition switch OFF.

7.Turn the ignition switch ON(II).

Is the low oil pressure light on?


YES - Go to 10.


NO - Go to 8.


8.Inspect the No. 16 (7.5A) fuse in the under-dash fuse/relay box.

Is the fuse OK?


YES - Go to 9.


NO - Repair short in the wire between No. 16 (7.5A) fuse and the gauge assembly. Also replace the No. 16 (7.5A) fuse.n


9.Inspect the No. 3 (50A) fuse in the under-hood fuse/relay box.

Is the fuse OK?


YES - Repair open in the wire between the No. 3 (50A) fuse and the gauge assembly. If the wires are OK, test the ignition switch.n


NO - Repair short in the wire between the No. 3 (50A) fuse and the under-hood fuse/relay box. Also replace the No. 3 (50A) fuse.n


10.Try to start the engine.

Does the engine start?


YES - Go to 11.


NO - Go to 14.


11.Turn the ignition switch OFF.

12.Connect ECM/PCM connector terminal E31 and body ground with a jumper wire.

 

13.Turn the ignition switch ON (II).

Is the MIL on?


YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


NO - Check for an open in the wires 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.n


14.Turn the ignition switch OFF.

15.Inspect the No. 20 (15A) fuse in the under-dash fuse/relay box.

Is the fuse OK?


YES - Go to 23.


NO - Go to 16.


16.Remove the blown No. 20 (15A) fuse in the under-dash fuse/relay box.

17.Remove the driver's side under cover.

18.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 1 (brown) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 

19.Check for continuity between body ground and PGM-FI main relay 1 4P connector terminals No. 2 and No. 3 individually.

 

Is there continuity?


YES - Repair short in the wire between the No. 20 (15A) fuse and the PGM-FI main relay 1. Also replace the No. 20 (15A) fuse.n


NO - Go to 20.

20.Disconnect each of the component or the connector sensors 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

 

Is there continuity?


YES - Go to 21.


NO - Replace the item that made continuity to body ground go away when disconnected. If the item is the ECM/PCM, update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
Also replace the No. 20 (15A) fuse.n


21.Disconnected the connectors of all following items.

  • 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

22.Check for continuity between PGM-FI main relay 1 4P connector terminals 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. 20 (15A) fuse.n


NO - Replace the PGM-FI main relay 1. Also replace the No. 20 (15A) fuse.n


23.Inspect the No. 11 (15A) fuse in the under-dash fuse/relay box.

Is the fuse OK?


YES - Go to 34.


NO - Go to 24.


24.Remove the blown No. 11 (15A) fuse in the under-dash fuse/relay box.

25.Disconnect ECM/PCM connector E (31P).

26.Check for continuity between ECM/PCM connector terminal E9 and body ground.

 

Is there continuity?


YES - Go to 27.


NO - Replace the No. 11 (15A) fuse, and update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


27.Remove the driver's side under cover.

28.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 2, (blue) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 

29.Check for continuity between ECM/PCM connector terminal E9 and body ground.

 

Is there continuity?


YES - Repair short in the wire between the No. 11 (15A) fuse and the ECM/PCM (E9), or the No. 11 (15A) fuse and the PGM-FI main relay 2. Also replace the No. 11 (15A) fuse.n


NO - Go to 30.


30.Disconnect the fuel pump 5P connector.

31.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 2. Also replace the No. 11 (15A) fuse.n


NO - Go to 32.


32.Reinstall PGM-FI main relay 2 (A).

 

33.Check for continuity between fuel pump 5P connector terminal No. 5 and body ground.

 

Is there continuity?


YES - Replace PGM-FI main relay 2. Also replace the No. 11 (15A) fuse.n


NO - Check the fuel pump, and replace it if necessary. Also replace the No. 11 (15A) fuse.n


34.Disconnect ECM/PCM connector E (31P).

35.Turn the ignition switch ON (II).

36.Measure voltage between ECM/PCM connector terminals E9 and body ground.

 

Is there battery voltage?


YES - Go to 37.


NO - Repair open in the wire between the No. 11 (15A) fuse and the ECM/PCM (E9).n

37.Turn the ignition switch OFF.

38.Measure voltage between ECM/PCM connector terminal E7 and body ground.

 

Is there battery voltage?


YES - Go to 43.


NO - Go to 39.


39.Remove the driver's side under cover.

40.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 1 (blown) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 

41.Measure voltage between PGM-FI main relay 1 4P connector terminal No. 3 and body ground.

 

Is there battery voltage?


YES - Go to 42.


NO - Repair open in the wire between the No. 20 (15A) fuse and PGM-FI main relay 1.n


42.Check for continuity between PGM-FI main relay 1 4P connector terminal No. 4 and ECM/PCM connector terminal E7.

 

Is there continuity?


YES - Test PGM-FI main relay 1. If the relay is OK, update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


NO - Repair open in the wire between PGM-FI main relay 1 and the ECM/PCM (E7).n

43.Reconnect ECM/PCM connector E (31P).

44.Turn the ignition switch ON (II).

45.Measure voltage between body ground and ECM/PCM connector terminals A2 and A3 individually.

 

Is there battery voltage?


YES - Go to 53.


NO - Go to 46.


46.Turn the ignition switch OFF.

47.Remove the driver's side under cover.

48.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 1 (brown) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 

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 51.


NO - Repair open in the wire between the No. 20 (15A) fuse and PGM-FI main relay 1.n


51.Turn the ignition switch OFF.

52.Check for continuity between PGM-FI main relay 1 4P connector terminal No. 1 and ECM/PCM connector terminals A2 and A3 individually.

 

Is there continuity?


YES - Replace the PGM-FI main relay 1.n


NO - Repair open in the wire between PGM-FI main relay 1 and the ECM/PCM (A2, A3).n

53.Measure voltage between body ground and ECM/PCM connector terminals A4, A5, A23 and A24 individually.

 

Is there less than 0.2 V?


YES - Repair open in the wire(s) that had more than 0.2 V between G101 and ECM/PCM (A4, A5, A23, A24).n


NO - Go to 54.


54.Measure voltage between body ground and ECM/PCM connector terminals A21.

 

Is there about 5 V?


YES - Go to 61.


NO - Go to 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 ECM/PCM connector terminal A21 with the ignition switch ON (II).

  • Manifold absolute pressure (MAP) sensor
  • CVT driven pulley speed sensor (CVT)
  • CVT speed sensor (CVT)

 

Is there about 5 V?


YES - Replace the sensor that restored 5 V when disconnected.n


NO - Go to 57.


57.Turn the ignition switch OFF.

58.Disconnect the 3P connectors from the following sensors.

  • Manifold absolute pressure (MAP) sensor
  • CVT driven pulley speed sensor (CVT)
  • CVT speed sensor (CVT)

59.Disconnect ECM/PCM connector A (31P).

60.Check for continuity between ECM/PCM connector terminal A21 and body ground.

 

Is there continuity?


YES - Repair short in the wire between ECM/PCM (A21) and the  MAP sensor, CVT driven pulley speed sensor (CVT) or  CVT speed sensor (CVT).n


NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


61.Measure voltage between body ground and ECM/PCM connector terminals A20.

 

Is there about 5 V?


YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


NO - Go to 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 ECM/PCM connector terminal A20 with the ignition switch ON (II).

  • Throttle position (TP) sensor
  • EGR valve position sensor
  • CVT drive pulley speed sensor (CVT)

 

Is there about 5 V?


YES - Replace the sensor that restored 5 V when disconnected.n


NO - Go to 64.


64.Turn the ignition switch OFF.

65.Disconnect the 3P connector from the following sensors.

  • Throttle position (TP) sensor
  • EGR valve position sensor
  • CVT drive pulley speed sensor (CVT)

66.Disconnect ECM/PCM connector A (31P).

67.Check for continuity between ECM/PCM connector terminal A20 and body ground.

 

Is there continuity?


YES - Repair short in the wire between the ECM/PCM (A20) and the TP sensor, EGR valve position sensor or CVT  drive pulley speed sensor (CVT).n


NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


68.Turn the ignition switch OFF.

69.Turn the ignition switch ON (II).

70.Measure voltage between ECM/PCM connector terminal E29 and body ground.

 

Is there about 5 V (or battery voltage)?


YES - Go to 74.


NO - Go to 71.


71.Turn the ignition switch OFF.

72.Disconnect the ECM/PCM connector E (31P).

73.Check for continuity between ECM/PCM connector terminal E29 and body ground.

 

Is there continuity?


YES - Repair short in the wire between the data link connector (or the service check connector) and the ECM/PCM (E29).n


NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


74.Turn the ignition switch OFF.

75.Disconnect the ECM/PCM connector E (31P).

76.Turn the ignition ON (II).

Is the MIL ON?


YES - Repair short in the wire between the gauge assembly and the ECM/PCM (E31). If the wires are OK, replace the gauge assembly.n


NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n