DLC Circuit Troubleshooting

If the ECM/PCM does not communicate with the OBD II scan tool, Honda PGM Tester, 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 & Body Ground

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   Is there battery voltage? 

   1. YES  - Go to step 2.
   2. NO  - Repair open in the wire between DLC terminal No. 16 and the ACGS (15A) 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 & No. 16

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   Is there battery voltage? 

   1. YES  - Go to step 3.
   2. NO  - Repair open in the wire between DLC terminal No. 4 and body ground (G401).
3. Measure voltage between DLC terminals No. 5 and No. 16.
   Fig 3: Measuring Voltage Between DLC Terminals No. 5 & No. 16

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there battery voltage? 

   1. YES  - Go to step 4.
   2. NO  - Repair open in the wire between DLC terminal No. 5 and body ground (G101).
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 & No. 7

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   Is there 8.5 V or more? 

   1. YES  - Go to step  10.
   2. NO  - Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect ECM/PCM connector A (32P). Make sure the OBD II scan tool or Honda PGM Tester is disconnected from the DLC.
8. Check for continuity between DLC terminal No. 7 and body ground.
   Fig 5: Checking Continuity Between DLC Terminal No. 7 & Body Ground

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   Is there continuity? 

   1. YES  - Repair short to ground in the wire between DLC terminal No. 7 and the ECM/PCM (A21). After repairing the wire, check the DTC with the OBD II scan tool/Honda PGM Tester and go to the DTC Troubleshooting index.
   2. NO  - Go to step 9.
9. Check for continuity between DLC terminal No. 7 and ECM/PCM terminal A21.
   Fig 6: Checking Continuity Between DLC Terminal No. 7 & ECM/PCM Terminal A21

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   Is there continuity? 

   1. YES  - Substitute a known-good ECM/PCM and recheck (see HOW TO SUBSTITUTE THE ECM/PCM FOR TESTING PURPOSES ). If the symptom/indication goes away, replace the original ECM/PCM.
   2. NO  - Repair open in the wire between DLC terminal No. 7 and the ECM/PCM (A21). After repairing the wire, check the DTC with the OBD II scan tool/Honda PGM Tester and go to the DTC Troubleshooting index.
10. Turn the ignition switch OFF.
11. Disconnect ECM/PCM connector A (32P). Make sure the OBD II scan tool or Honda PGM Tester 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 & No. 7

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 0 V? 

    1. YES  - Substitute a known-good ECM/PCM and recheck (see HOW TO SUBSTITUTE THE ECM/PCM FOR TESTING PURPOSES ). If the symptom/indication goes away, replace the original ECM/PCM.
    2. NO  - Repair short to power in the wire between the DLC terminal No. 7 and the ECM/PCM (A21). After repairing the wire, check the DTC with the OBD II scan tool/Honda PGM Tester and go to the DTC Troubleshooting index.