2003 Honda Insight StandardFACTORY OEM SERVICE PROCEDURE

DLC Circuit Troubleshooting

  • If the ECM does not communicate with the HDS, do this troubleshooting procedure.
  • Check that the MIL circuit is normal, then do this troubleshooting.
  1. Measure voltage between DLC terminal No. 16 and body ground.
    Fig 1: Measuring Voltage Between DLC Terminal No. 16 And Body Ground
    G03680948Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 2.
    2. NO  - Repair open in the wire between DLC terminal No. 16 and the No. 18 (7.5 A) 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 16
    G03680949Courtesy of AMERICAN HONDA MOTOR CO., INC.

    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.
  3. Measure voltage between DLC terminals No. 5 and No. 16.
    Fig 3: Measuring Voltage Between DLC Terminals No. 5 And 16
    G03680950Courtesy 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.
  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 7
    G03680951Courtesy of AMERICAN HONDA MOTOR CO., INC.

    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, and wait for 10 seconds.
  7. Disconnect ECM connector A (32P).
  8. Check for continuity between DLC terminal No. 7 and body ground.
    Fig 5: Checking Continuity Between DLC Terminal No. 7 And Body Ground
    G03680952Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Repair short to ground in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with the HDS, and go to the indicated DTC TROUBLESHOOTING .
    2. NO  - Go to step 9.
  9. Check for continuity between DLC terminal No. 7 and ECM terminal A21.
    Fig 6: Checking Continuity Between DLC Terminal No. 7 And ECM Terminal A21
    G03680953Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Update the ECM if it does not have the latest software, or substitute a known-good ECM; 2000-2001 M/T models (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES (2000-2001 M/T MODELS) ), 2002-2006 M/T models and CVT model (see ECM UPDATING AND SUBSTITUTION FOR TESTING-2002-2006 M/T MODELS AND CVT MODEL ), then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM (see ECM REPLACEMENT ).
    2. NO  - Repair open in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check the DTC with the HDS, and go to the indicated DTC TROUBLESHOOTING .
  10. Turn the ignition switch OFF, and wait for 10 seconds.
  11. Disconnect ECM connector A (32P).
  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 7
    G03680954Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 0 V? 

    1. YES  - Update the ECM if it does not have the latest software, or substitute a known-good ECM; 2000-2001 M/T models (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES (2000-2001 M/T MODELS) ), 2002-2006 M/T models and CVT model (see ECM UPDATING AND SUBSTITUTION FOR TESTING-2002-2006 M/T MODELS AND CVT MODEL ), then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM (see ECM REPLACEMENT ).
    2. NO  - Repair short to power in the wire between DLC terminal No. 7 and the ECM (A21). After repairing the wire, check for DTCs with the HDS, and go to the indicated DTC TROUBLESHOOTING .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.