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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM: Blower motor operation is malfunctioning under Starting Fan Speed Control.

Fig 1: Blower Motor Operation Description Chart
G01995649Courtesy of NISSAN MOTOR CO., U.S.A.
  1. CHECK POWER SUPPLY FOR FAN CONTROL AMP. 
    Fig 2: Checking Fan Control Amp. Terminals Voltage
    G01995650Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 3: Fan Control Amp. Terminals Voltage Chart
    G01995651Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes: GO TO 2.
    2. No: GO TO  8.
  2. CHECK BODY GROUND CIRCUIT FOR FAN CONTROL AMP. 
    Fig 4: Checking Fan Control Amp. Terminals Voltage
    G01995652Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes: Reconnect fan control amp. harness connector and GO TO 3.
    2. No: Repair harness or connector.
      Fig 5: Fan Control Amp. Terminals Voltage Chart
      G01995653Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK VOLTAGE FOR FAN CONTROL AMP. 

    Set up Self-Diagnosis   STEP 4.

    Fig 6: Checking Fan Control Amp. Terminals Voltage
    G01995654Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 4.
    2. NG:
      1. If the voltage is less than 2.5V, replace fan control amp.
        Fig 7: Fan Control Amp. Terminals Voltage Chart
        G01995655Courtesy of NISSAN MOTOR CO., U.S.A.
      2. If the voltage is more than 3.0V, GO TO 4.
      3. Go to "FUNCTION CONFIRMATION PROCEDURE", SELF-DIAGNOSIS and perform Self-Diagnosis   STEP 4.

        Confirm that blower motor operation is normal.

  4. CHECK FAN CONTROL AMP. 

    Refer to FAN CONTROL AMPLIFIER .

    OK or NG 

    1. OK: GO TO 5.
    2. NG:
      1. Replace fan control amp.
      2. Go to "FUNCTION CONFIRMATION PROCEDURE", SELF-DIAGNOSIS and perform self-diagnosis   STEP 4.

        Confirm that blower motor operation is normal.

  5. CHECK FAN CONTROL AMP. CIRCUIT BETWEEN FAN CONTROL AMP. AND AUTO AMP. (LCU) 
    1. Disconnect auto amp. (LCU) and fan control amp. harness connector.
      Fig 8: Checking Fan Control Amp. Terminals & Auto Amp. Terminals Voltage (LCU)
      G01995656Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist.

    If OK, check harness for short.

    Fig 9: Fan Control Amp. Terminals & Auto Amp. Terminals Continuity Chart
    G01995657Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 6.
    2. NG: Repair harness or connector.
  6. CHECK FAN FEEDBACK CIRCUIT 

    Reconnect auto amp. (LCU) harness connector.

    Fig 10: Checking Auto Amp. Connector Terminals Voltage (LCU)
    G01995658Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes: GO TO 7.
    2. No:
      • Check power supply circuit and 15A fuses [Nos. 10 and 11, located in the fuse block (J/B)].
        Fig 11: Auto Amp. (LCU) Harness Connector Terminals Voltage Chart
        G01995659Courtesy of NISSAN MOTOR CO., U.S.A.
      • Refer to POWER DISTRIBUTION in SYSTEM WIRING DIAGRAMS - ALTIMA article.
        • If OK, check for open circuit in wiring harness. Repair or replace as necessary.
        • If NG, replace fuse and check wiring harness for short circuit. Repair or replace as necessary.
  7. CHECK POWER SUPPLY FOR AUTO AMP. 
    Fig 12: Checking Auto Amp. Connector Terminals Voltage
    G01995660Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes:
      1. Replace auto amp.
      2. Go to "FUNCTION CONFIRMATION PROCEDURE", SELF-DIAGNOSIS and perform Self-Diagnosis   STEP 4.

        Confirm that blower motor operation is normal.

    2. No: GO TO  10.
      Fig 13: Auto Amp. Connector Terminals Voltage Chart
      G01995661Courtesy of NISSAN MOTOR CO., U.S.A.
  8. CHECK POWER SUPPLY FOR BLOWER MOTOR 

    Disconnect blower motor harness connector.

    Fig 14: Blower Motor Harness Connector Terminals Voltage Chart
    G01995662Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes: GO TO 9.
    2. No: Check power supply circuit and 15A fuses [Nos. 10 and 11, located in the fuse block (J/B)].
      Fig 15: Checking Blower Motor Harness Connector Terminals Voltage
      G01995663Courtesy of NISSAN MOTOR CO., U.S.A.
      • Check blower motor relay.
      • If OK, check for open circuit in wiring harness. Repair or replace as necessary.
      • If NG, replace fuse and check wiring harness for short circuit. Repair or replace as necessary.
  9. CHECK CIRCUIT CONTINUITY BETWEEN BLOWER MOTOR AND FAN CONTROL AMP. 

    Disconnect blower motor connector and auto amp. (LCU) connector.

    Fig 16: Blower Motor & Fan Control Amp. Connector Terminals Continuity Chart
    G01995664Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: Check blower motor. Refer to BLOWER MOTOR .
      1. If NG, replace blower motor.
      2. Go to "FUNCTION CONFIRMATION PROCEDURE", SELF-DIAGNOSIS and perform self-diagnosis   STEP 4.

        Confirm that blower motor operation is normal.

        Fig 17: Checking Circuit Continuity Between Blower Motor & Fan Control Amp. Connector Terminals
        G01995665Courtesy of NISSAN MOTOR CO., U.S.A.
    2. NG: Repair harness or connector.
  10. CHECK BLOWER MOTOR CIRCUIT BETWEEN BLOWER MOTOR AND AUTO AMP. (LCU) 
    Fig 18: Blower Motor & Auto Amp. (LCU) Connector Terminals Continuity Chart
    G01995666Courtesy of NISSAN MOTOR CO., U.S.A.

    Continuity should exist. 

    If OK, check harness for short.

    OK or NG 

    1. OK: INSPECTION END
    2. NG: Repair harness or connector.
      Fig 19: Checking Circuit Continuity Between Blower Motor & Auto Amp. (LCU) Connector Terminals
      G01995667Courtesy of NISSAN MOTOR CO., U.S.A.
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