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HOMESERVICE MANUALSHONDA2002CIVIC SIREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 127 (CHARGING SYSTEM)ALTERNATOR CONTROL CIRCUIT TROUBLESHOOTING
2002 Honda Civic Si

Alternator Control Circuit Troubleshooting

2002 Honda Civic SiSECTION Alternator Control Circuit Troubleshooting
WARNING: This page is about a different car, the 2006 Honda Odyssey and 2005 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check for proper operation of the electrical load detector (ELD) by checking the malfunction indicator lamp (MIL) (see GENERAL TROUBLESHOOTING INFORMATION ).
  2. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) and check for DTCs (see HOW TO USE THE HDS (HONDA DIAGNOSTIC SYSTEM) ). If a DTC is present, diagnose and repair the cause before continuing with this test.
  3. Disconnect the alternator 4P connector from the alternator.
  4. Start the engine, and turn on the headlights to high beam.
  5. Measure the voltage between alternator 4P connector terminal No. 2 and the positive terminal of the battery.
    Fig 1: Measuring Voltage Between Alternator 4P Connector Terminal No. 2 And Positive Terminal Of Battery
    G03703552Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 1 V or less? 

    1. YES  - Go to step 6.
    2. NO  - Go to step  9.
  6. Jump the SCS line with the HDS, then turn the ignition switch OFF.
    NOTE: This step must be done to protect the powertrain control module (PCM) from damage.
  7. Disconnect PCM connector C (44P).
  8. Check for continuity between PCM connector terminal C38 and body ground.
    Fig 2: Checking Continuity Between PCM Connector Terminal C38 And Body Ground
    G03703553Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Repair a short in the wire between the alternator and the PCM.
    2. NO  - Update the PCM if it does not have the latest software (see PCM UPDATING AND SUBSTITUTION FOR TESTING ), or substitute a known-good PCM (see HOW TO SUBSTITUTE THE PCM ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM (see PCM REPLACEMENT ).
  9. Jump the SCS line with the HDS, then turn the ignition switch OFF.
    NOTE: This step must be done to protect the powertrain control module (PCM) from damage.
  10. Disconnect PCM connector C (44P).
  11. Check for continuity between PCM connector terminal C38 and alternator 4P connector terminal No. 2.
    Fig 3: Checking Continuity Between PCM Connector Terminal C38 And Alternator 4P Connector Terminal No. 2
    G03703554Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Replace the alternator (see ALTERNATOR REMOVAL AND INSTALLATION  ) or repair the alternator (see ALTERNATOR OVERHAUL  ).
    2. NO  - Repair an open in the wire between the alternator and the PCM.
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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.