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 81. 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*1 (go to 13). 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 (A/T), CVT speed sensor (A/T).
  • 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 (A/T).
    *1: With inertia switch
    *2: Without inertia switch

6.Turn the ignition switch OFF.

7.Press the inertia switch button.

8.Turn the ignition switch ON(II).

Does the MIL come on for 2 seconds after the ignition switch is turned ON (II)?


YES - Intermittent failure system is OK at this time.n


NO - Go to 9.


9.Turn the ignition switch OFF.

10.Disconnect the inertia switch 3P connector.

11.Connect the intertia switch 3P connector terminals No. 1 and No. 3 with a jumper wire.

 

12.Turn the ignition switch ON(II).

Does the MIL come on for 2 seconds after the ignition switch is turned ON (II)?


YES - Replace the inertia switch.n


NO - Go to 13.

13.Turn the ignition switch OFF.

14.Turn the ignition switch ON(II).

Is the low oil pressure light on?


YES - Go to 17.


NO - Go to 15.


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

Is the fuse OK?


YES - Go to 16.


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


16.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


17.Try to start the engine.

Does the engine start?


YES - Go to 18.


NO - Go to 21.


18.Turn the ignition switch OFF.

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

 

20.Turn the ignition switch ON (II).

Is the MIL on?


YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, 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


21.Turn the ignition switch OFF.

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

Is the fuse OK?


YES - Go to 30.


NO - Go to 23.


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

24.Remove the driver's side under cover.

25.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.

 

26.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 27.

27.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 28.


NO - Replace the item that made continuity to body ground go away when disconnected. If the item is the ECM/PCM, substitute a known-good ECM/PCM and recheck.
If the symptom/indication goes away, replace the original  ECM/ PCM.
Also replace the No. 20 (15A) fuse.n


28.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

29.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


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

Is the fuse OK?


YES - Go to 43.


NO - Go to 31.


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

32.Disconnect the negative cable from the battery.

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

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

 

Is there continuity?


YES - Go to 35.


NO - Replace the No. 11 (15A) fuse, and substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original  ECM/ PCM.n


35.Remove the driver's side under cover.

36.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.

 

37.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 38.


38.Disconnect the fuel pump 5P connector.

39.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 40.


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

 

41.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


42.Disconnect the negative cable from the battery.

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

44.Reconnect the negative cable from the battery.

45.Turn the ignition switch ON (II).

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

 

Is there battery voltage?


YES - Go to 47.


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

47.Turn the ignition switch OFF.

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

 

Is there battery voltage?


YES - Go to 53.


NO - Go to 49.


49.Remove the driver's side under cover.

50.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.

 

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

 

Is there battery voltage?


YES - Go to 52.


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


52.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, substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original  ECM/ PCM.n


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

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

54.Reconnect the negative cable from the battery.

55.Turn the ignition switch ON (II).

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

 

Is there battery voltage?


YES - Go to 64.


NO - Go to 57.


57.Turn the ignition switch OFF.

58.Remove the driver's side under cover.

59.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.

 

60.Turn the ignition switch ON (II).

61.Measure voltage between PGM-FI main relay 1 4P connector terminal No. 2 and body ground.

 

Is there battery voltage?


YES - Go to 62.


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


62.Turn the ignition switch OFF.

63.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

64.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 65.


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

 

Is there about 5 V?


YES - Go to 73.


NO - Go to 66.

66.Turn the ignition switch OFF.

67.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 (A/T)
  • CVT speed sensor (A/T)

 

Is there about 5 V?


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


NO - Go to 68.


68.Turn the ignition switch OFF.

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

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

70.Disconnect the negative cable from the battery.

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

72.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 (A/T) or  CVT speed sensor (A/T).n


NO - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM.n


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

 

Is there about 5 V?


YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original  ECM/ PCM.n


NO - Go to 74.

74.Turn the ignition switch OFF.

75.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 (A/T)

 

Is there about 5 V?


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


NO - Go to 76.


76.Turn the ignition switch OFF.

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

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

78.Disconnect the negative cable from the battery.

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

80.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 (A/T).n


NO - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original  ECM/ PCM.n


81.Turn the ignition switch OFF.

82.Turn the ignition switch ON (II).

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

 

Is there about 5 V (or battery voltage)?


YES - Go to 88.


NO - Go to 84.


84.Turn the ignition switch OFF.

85.Disconnect the negative cable from the battery.

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

87.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 - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original  ECM/ PCM.n


88.Turn the ignition switch OFF.

89.Disconnect the negative cable from the battery.

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

91.Reconnect the negative cable from the battery.

92.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 - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original  ECM/ PCM.n