DLC Circuit Troubleshooting

If the ECM does not communicate with the HDS or a scan tool, or I/M test equipment, do this troubleshooting procedure.

1. Measure voltage between DLC terminal No. 16 and body ground.
   Fig 1: Measuring Voltage Between DLC Terminal No. 16 And Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   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.
   Fig 2: Measuring Voltage Between DLC Terminals No. 4 And No. 16

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   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.
   Fig 3: Measuring Voltage Between DLC Terminals No. 5 And No. 16

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there battery voltage? 

   YES:  Go to step 4.

   NO:  Repair open in the wire between DLC terminal No. 5 and the ECM (E3) or ECM (A23, A24) and body ground.

4. Turn the ignition switch ON (II).
5. Measure voltage between DLC terminals No. 5 and No. 7.
   Fig 4: Measuring Voltage Between DLC Terminals No. 5 And No. 7

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there 8.5 V or more? 

   YES:  Go to step  10.

   NO:  Go to step 6.

6. Turn the ignition switch OFF.
7. Disconnect ECM connector E (31P). Make sure the HDS or a scan tool is disconnected from the DLC.
8. Check for continuity between DLC terminal No. 7 and body ground.
   Fig 5: Checking For Continuity Between DLC Terminal No. 7 And Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there continuity? 

   YES:  Repair short to ground in the wire between DLC terminal No. 7 and the ECM (E23). After repairing the wire, check the DTC with the HDS or a scan tool, and go to the indicated DTC's troubleshooting.

   NO:  Go to step 9.

9. Check for continuity between DLC terminal No. 7 and ECM terminal E23.
   Fig 6: Checking For Continuity Between DLC Terminal No. 7 And ECM Terminal E23

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there continuity? 

   YES:  Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck (see ECM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM, replace the original ECM.

   NO:  Repair open in the wire between DLC terminal No. 7 and the ECM (E23). After repairing the wire, check the DTC with the HDS or a scan tool, and go to the indicated DTC's troubleshooting.

10. Turn the ignition switch OFF.
11. Disconnect ECM connector E (31P). Make sure the HDS or a scan tool is disconnected from the DLC.
12. Turn the ignition switch ON (II).
13. Measure voltage between DLC terminals No. 5 and No. 7.
    Fig 7: Measuring Voltage Between DLC Terminals No. 5 And No. 7

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 0 V? 

    YES:  Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck (see ECM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM, replace the original ECM.

    NO:  Repair short to power in the wire between the DLC terminal No. 7 and the ECM (E23). After repairing the wire, check the DTC with the HDS or a scan tool, and go to the indicated DTC's troubleshooting.