DLC Circuit Troubleshooting

DLC Circuit Troubleshooting

NOTE: Do this troubleshooting if the MCM does not communicate with the OBD II scan tool, Honda PGM Tester, or I/M test equipment.





1. Measure voltage between DLC terminal No. 16 and body ground.
Is there battery voltage?
YES - Go to step 2.
NO - Repair open in the wire between DLC terminal No. 16 and the No. 9 BACK UP (7.5A) fuse in the under-hood fuse/relay box.





2. Measure voltage between DLC terminals No. 4 and No. 16.
Is there battery voltage?
YES - Go to step 3.
NO - Repair open in the wire between DLC terminal No. 4 and body ground.





3. Measure voltage between DLC terminals No. 5 and No. 16.
Is there battery voltage?
YES - Go to step 4.
NO - Repair open in the wire between DLC terminal No. 5 and the ECM (E3).
4. Turn the ignition switch ON (II).





5. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 8.5 V or more?
YES - Go to step 13.
NO - Go to step 6.
6. Turn the ignition switch OFF.
7. Turn the battery module switch OFF.
8. Remove the IPU lid.
9. Disconnect MCM connector A (31P). Make sure the OBD II scan tool or Honda PGM Tester is disconnected from the DLC.





10. Check for continuity between DLC terminal No. 7 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between DLC terminal No. 7 and the MCM (A28). After repairing the wire, check for a DTC with the OBD II scan tool/Honda PGM Tester. If there is a DTC, go to the DTC Troubleshooting Index.
NO - Go to step 11.





11. Connect DLC terminal No. 7 to body ground with a jumper wire.





12. Check for continuity between MCM terminal A28 and body ground.
Is there continuity?
YES - Update the MCM if it does not have the latest software, or substitute a known-good MCM, then recheck. If the symptom/indication goes away with a known-good MCM, replace the original MCM.
NO - Repair open in the wire between DLC terminal No. 7 and the MCM (A28). After repairing the wire, check for a DTC with the OBD II scan tool/Honda PGM Tester. If there is a DTC, go to the DTC Troubleshooting Index.
13. Turn the ignition switch OFF.
14. Turn the battery module switch OFF.
15. Remove the IPU lid.
16. Disconnect MCM connector A (31P). Make sure the OBD II scan tool or Honda PGM Tester is disconnected from the DLC.
17. Turn the ignition switch ON (II).





18. Measure voltage between DLC terminals No. 5 and No. 7.
Is there 0 V?
YES - Update the MCM if it does not have the latest software, or substitute a known-good MCM, then recheck. If the symptom/indication goes away with a known-good MCM, replace the original MCM.
NO - Repair short to power in the wire between the DLC terminal No. 7 and the MCM (A28). After repairing the wire, check for a DTC with the OBD II scan tool/Honda PGM Tester. If there is a DTC, go to the DTC Troubleshooting Index.