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HOMESERVICE MANUALSACURA2004TL AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISIDLE CONTROL SYSTEMALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING2004-2005 MODELS
2004 Acura TL Automatic

2004-2005 models

2004 Acura TL AutomaticSECTION 2004-2005 models
  1. Start the engine, and let it idle.
  2. Monitor the ALTERNATOR in the DATA LIST with the HDS.
  3. Check if the indicated percentage varies when the headlight switch is on.

    Does the percentage vary? 

    1. YES  -The alternator signal circuit is OK.
    2. NO  -Go to step 4.
  4. Turn the headlight switch and ignition switch OFF.
  5. Disconnect the alternator 4P connector.
  6. Turn the ignition switch ON (II).
  7. Measure voltage between ECM/PCM connector terminals E3 and E12.
    Fig 1: Measuring Voltage Between ECM/PCM Connector Terminals E3 And E12
    G03659673Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    1. YES  -Go to step 8.
    2. NO  -Go to step 13.
  8. Turn the ignition switch OFF.
  9. Jump the SCS line with the HDS.
  10. Disconnect ECM/PCM connector E (31P).
  11. Connect alternator 4P connector terminal No. 4 to body ground with a jumper wire.
    Fig 2: Connecting Alternator 4P Connector Terminal 4 To Body Ground With Jumper Wire
    G03659674Courtesy of AMERICAN HONDA MOTOR CO., INC.
  12. Check for continuity between body ground and ECM/PCM connector terminal E12.
    Fig 3: Checking Continuity Between Body Ground And ECM/PCM Connector Terminal E12
    G03659675Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  -Test the alternator (see ALTERNATOR AND REGULATOR CIRCUIT TROUBLESHOOTING ).
    2. NO  -Repair open in the wire between the ECM/PCM (E12) and the alternator.
  13. Turn the ignition switch OFF.
  14. Jump the SCS line with the HDS.
  15. Disconnect ECM/PCM connector E (31P).
  16. Check for continuity between body ground and ECM/PCM connector terminal E12.
    Fig 4: Checking Continuity Between Body Ground And ECM/PCM Connector Terminal E12
    G03659676Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  -Repair short in the wire between the ECM/PCM (E12) and the alternator.
    2. NO  -Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/ PCM (see HOW TO TROUBLESHOOT CIRCUITS AT THE ECM/PCM ), then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ).
RENDER: 1.0x

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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.