MIL Stays ON

MIL Circuit Troubleshooting
1. Turn the ignition switch ON (II) and watch the Malfunction Indicator Light (MIL).
Does the MIL come on and stay on?
YES-If the MIL always come on and stays on, go to step 2. But if the MIL sometimes works normally, first check for these problems.
- An intermittent short in the wire between the ECM/PCM (A10) and the data link connector.
- An intermittent open in the wire between the ECM/PCM (A21) and the data link connector.
- An intermittent short in the wire between the ECM/PCM (A18) and the gauge assembly.




2. Turn the ignition switch ON (II), and measure voltage between body ground and ECM/PCM connector terminals B2, B10, B20 and B22 individually.
Is there less than 1.0 V?
YES-Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM.
Diagnostic Strategies

NO-Repair the open in the wire(s) between that had more than 1.0 V between G101 and ECM/PCM (B2, B10, B20, B22).
3. Connect an OBD II scan tool/Honda PGM tester.
4. Turn the ignition switch ON (II), and read the OBD II scan tool/Honda PGM tester.
Are any DTCs indicated?
YES-Go to the DTC Troubleshooting Index.
Diagnostic Trouble Code Descriptions

NO-Go to step 5.

5. Turn the ignition switch OFF, and disconnect the ECM/PCM connector A (32P).




6. Check for continuity between body ground and data link connector (DLC) (16P) terminal No.15.
Is there continuity?
YES-Repair short in the wire between the DLC and the ECM/PCM (A21).
NO-Go to step 7.




7. Check for continuity between ECM/PCM connector terminal A21 and DLC (16P) terminal No.15.
Is there continuity?
YES-Go to step 8.
NO-Repair open in the wire between the DLC and the ECM/PCM (A21).




8. Turn the ignition switch OFF, then turn it back ON (II) and measure voltage between ECM/PCM connector terminal A10 and body ground.
Is there approximately 5 V?
YES-Go to step 9.
NO-Repair short in the wire between the DLC and the ECM/PCM (A10).
9. Turn the ignition switch OFF, disconnect the ECM/PCM connector A (32P), and turn the ignition switch ON (II).
Is the MIL on?
YES-Repair short in the wire between the gauge assembly and the ECM/PCM (A 18).
NO-Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM.
Diagnostic Strategies