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Home >> Honda >> 2003 >> Civic Si >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Idle Control System (Hatchback) >> Alternator FR Signal Circuit Troubleshooting
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Alternator FR Signal Circuit Troubleshooting

  1. Disconnect the alternator 4P connector from the alternator.
  2. Turn the ignition switch ON (II).
  3. Measure voltage between ECM connector terminals A24 and B13.
    1. Is there about 5 V? 
      1. YES:  Go to step 4.
      2. NO:  Go to step  13.
      2. Fig 1: Measuring Voltage Between ECM Connector Terminals A24 And B13
      G01399531Courtesy of AMERICAN HONDA MOTOR CO., INC.
  4. Turn the ignition switch OFF.
  5. Reconnect the alternator 4P connector.
  6. Start the engine. Hold the engine at 3,000 RPM with no load (in neutral) until the radiator fan comes on, then let it idle.
  7. Measure voltage between ECM connector terminals A24 and B13.
    1. Does the voltage decrease when the headlights and rear window defogger are turned on? 
      1. YES:  The alternator FR signal is OK.
      2. NO:  Go to step 8.
  8. Turn the ignition switch OFF.
  9. Disconnect ECM connector B (24P).
  10. Disconnect the alternator 4P connector.
  11. Connect alternator 4P connector terminal No. 4 to body ground with a jumper wire.
    Fig 2: Connecting Alternator 4P Connector Terminal No. 4 To Body Ground With A Jumper Wire
    G01399532Courtesy of AMERICAN HONDA MOTOR CO., INC.
  12. Check for continuity between body ground and ECM connector terminal B13.
    1. Is there continuity? 
      1. YES:  Test the alternator (see CHARGING SYSTEM ).
      2. NO:  Repair open in the wire between the ECM (B13) and the alternator.
      2. Fig 3: Checking For Continuity Between Body Ground And ECM Connector Terminal B13
      G01399533Courtesy of AMERICAN HONDA MOTOR CO., INC.
  13. Turn the ignition switch OFF.
  14. Disconnect ECM connector B (24P).
  15. Check for continuity between body ground and ECM connector terminal B13.
    1. Is there continuity? 
      1. YES:  Repair short in the wire between the ECM (B13) and the alternator.
      2. NO:  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.
      2. Fig 4: Checking For Continuity Between Body Ground And ECM Connector Terminal B13
      G01399534Courtesy of AMERICAN HONDA MOTOR CO., INC.
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