MIL Circuit Troubleshooting
MIL Circuit TroubleshootingNOTE: Information marked with an asterisk (*) applies to '02 model.
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 PCM?
YES - Go to step 3.
NO - Go to troubleshooting "DLC Circuit Troubleshooting".
3. Check the scan tool/Honda PGM Tester for DTCs.
Are any DTCs indicated?
YES - Go to the DTC Troubleshooting Index.
NO - Go to step 4.
4. Turn the ignition switch OFF.
5. Turn the ignition switch OFF.
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 come on and stays on, go to step 26. But if the MIL sometimes works normally, first check for these problems.
- An intermittent short in the wire between the PCM (A10) and the Data Link Connector (DLC) connector.
- An intermittent open in the wire between the PCM (A21) and the DLC.
- An intermittent short in the wire between the PCM (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.9 BACK UP LIGHT, INSTRUMENT LIGHT (7.5 A) fuse in the driver's under-dash fuse/relay box.
- A loose ACG S (15 A) fuse in the under-hood fuse/relay box.
- A loose No.1 FUEL PUMP (15 A) fuse in the driver's under-dash fuse/relay box.
- A poor connection at PCM terminal A18.
- An intermittent open in the GRN/ORN wire between the PCM (A18) and the gauge assembly.
- An intermittent short in the wire between the PCM (C19) and the manifold absolute pressure (MAP) sensor.
- An intermittent short in the wire between the PCM (C28) and the throttle position (TP) sensor, Exhaust Gas Recirculation (EGR) valve position sensor, the fuel tank pressure (FTP) sensor*.
6. Turn the ignition switch OFF and then ON (II) again.
Is the low oil pressure light on?
YES - Go to step 7.
NO - Check for these problems:
- A blown No.9 BACK UP LIGHT, INSTRUMENT LIGHT (7.5 A) fuse in the driver's under-dash fuse/relay box.
- A short or open in the wire between No.9 BACK UP LIGHT, INSTRUMENT LIGHT (7.5 A) fuse and the gauge assembly.
7. Try to start the engine.
Does the engine start?
YES - Go to step 8.
NO - Go to step 11.
8. Turn the ignition switch OFF.
9. Connect PCM connector terminal A18 and body ground with a jumper wire.
10. Turn the ignition switch ON (II).
Is the MIL on?
YES - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.
NO - Check for an open in the wires between the PCM (A18) and the gauge assembly. Also check for a blown MIL bulb.
11. Turn the ignition switch OFF.
12. Inspect the ACG S (15 A) fuse in the under-hood fuse/relay box.
Is the fuse OK?
YES - Go to step 13.
NO - Check for these problems:
- A short in the wire between the ACG S (15 A) fuse and the PGM-FI main relay.
- A short in the wire between the PGM-FI main relay and the PCM, injectors, or IAC valve.
- A blown ACG S (15 A) fuse in the driver's under-dash fuse/relay box.
13. Inspect the No.1 FUEL PUMP (15 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?
YES - Go to step 14.
NO - Check for these problems:
- A short in the wire between the No.1 FUEL PUMP (15 A) fuse and the PGM-FI main relay.
- A short in the wire between the PGM-FI main relay and the fuel pump.
- A blown the No.1 FUEL PUMP (15 A) fuse in the under-dash fuse/relay box.
- A faulty PGM-FI main relay or a faulty fuel pump.
14. Disconnect the negative cable from the battery.
15. Disconnect PCM connector C (31P).
16. Check for continuity between body ground and PCM connector terminals C19 and C28 individually.
Is there continuity?
YES - Go to step 17.
NO - Go to step 18.
17. Disconnect the 3P connector from each of these sensors, one at a time, and check for continuity between body ground and PCM connector terminal C19 and C28 individually.
- Manifold Absolute Pressure (MAP) sensor
- Exhaust Gas Recirculation (EGR) valve position sensor
- Throttle Position (TP) sensor
- Fuel Tank Pressure (FTP) sensor*
Is there continuity?
YES - Repair short to body ground in the wire between PCM (C19) and the MAP sensor, or PCM (C28) and the TP sensor, EGR valve position sensor or FTP sensor*.
NO - Replace the sensor that made continuity to body ground go away when disconnected.
18. Disconnect the injectors and IAC valve connectors.
19. Reconnect the negative cable to the battery.
20. Turn the ignition switch ON (II).
21. Measure voltage between body ground and the PCM connector terminals B1 and B9 individually.
Is there battery voltage?
YES - Go to step 22.
NO - Check for these problems:
- An open in the wire(s) between the PGM-FI main relay and PCM connector terminals B1 and B9.
- Poor connections at the PGM-FI main relay.
- A faulty PGM-FI main relay. If necessary, repair or replace the part.
22. Disconnect the negative cable from the battery.
23. Reconnect the connectors to the sensors, then reconnect PCM connector C (31P).
24. Reconnect the negative cable to the battery.
25. Turn the ignition switch ON (II), and measure voltage between body ground and PCM connector terminals B2, 810, B20 and 822 individually.
Is there less than 1.0 V?
YES - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.
NO - Repair the open in the wire(s) that had more than 1.0 V between G101 and the PCM (82, 810, B20, 822).
26. Turn the ignition switch OFF, then turn it back ON (11) and measure voltage between PCM connector terminal A10 and body ground.
Is there about 5 V (or battery voltage)?
YES - Go to step 27.
NO - Go to step 31.
27. Turn the ignition switch OFF.
28. Disconnect the negative cable from the battery.
29. Disconnect PCM connector A (32P).
30. Check for continuity between PCM connector terminal A10 and body ground.
Is there continuity?
YES - Repair short in the wire between the data link connector and the PCM (E29).
NO - Substitute a known-good PCM and recheck. If symptom/indication goes away, replace the original PCM.
31. Turn the ignition switch OFF.
32. Disconnect the negative cable from the battery.
33. Disconnect PCM connector A (32P).
34. Reconnect the negative cable to the battery.
35. Turn the ignition switch ON (II).
Does the MIL stay on?
YES - Repair short in the wire between the gauge assembly and the PCM (A18).
NO - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.