LEMON Manuals: Even more car manuals for everyone
Home >> Nissan-Datsun >> 2004 >> Altima S, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 923 (Automatic Air Conditioner) >> Trouble Diagnosis >> Multiplex Communication Circuit >> Diagnosis Procedure For Multiplex Communication

Diagnosis Procedure For Multiplex Communication

WARNING: This page is about a different car, the 2008 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM: A/C system cannot be controlled.

Fig 1: Multiplex Communication Diagnosis Circuit
G04917630Courtesy of NISSAN MOTOR CO., U.S.A.
  1. CHECK FOR UNIFIED METER AND A/C AMP. OUTPUT 
    1. Turn ignition switch ON.
    2. Check multiplex communication signal between unified meter and A/C amp. harness connector M49 terminal 10 and ground using an oscilloscope.
    TERMINALS AND VOLTAGE REFERENCE CHART

    Terminal Voltage
    (+) (-)
    Unified meter and A/C amp. connector Terminal No.
    M49 10 Ground
    G04917631Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 2: Checking Unified Meter And A/C Amp. Output Connector Terminal
    G04917632Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  3.

    NG: GO TO  2.

  2. CHECK CIRCUIT CONTINUITY BETWEEN FRONT AIR CONTROL AND UNIFIED METER AND A/C AMP  .
    1. Turn ignition switch OFF.
    2. Disconnect front air control connector and unified meter and A/C amp. connector.
    3. Check continuity between front air control harness connector M201 (B) terminal 3 and unified meter and A/C amp. harness connector M49 (A) terminal 10.

      3 - 10: Continuity should exist  .

    Fig 3: Checking Continuity Between Front Air Control And Unified Meter And A/C Amp. Connector Terminal
    G04917633Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: Replace unified meter and A/C amp. Refer to "UNIFIED METER AND A/C AMP ".

    NG: Repair harness or connector.

  3. CHECK FOR UNIFIED METER AND A/C AMP. INPUT 

    Confirm multiplex communication signal between unified meter and A/C amp. harness connector M49 terminal 20 and ground using an oscilloscope.

    UNIFIED METER AND A/C AMP. INPUT CHART

    Terminal Voltage
    (+) (-)
    Unified meter and A/C amp. connector Terminal No.
    M49 20 Ground
    G04917634Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 4: Checking Unified Meter And A/C Amp. Input Connector Terminal
    G04917635Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: Replace unified meter and A/C amp. Refer to "UNIFIED METER AND A/C AMP ."

    NG: GO TO  4.

  4. CHECK CIRCUIT CONTINUITY BETWEEN FRONT AIR CONTROL AND UNIFIED METER AND A/C AMP  .
    1. Turn ignition switch OFF.
    2. Disconnect front air control connector and unified meter A/C amp. connector.
    3. Check continuity between front air control harness connector M201 (B) terminal 4 and unified meter and A/C amp. harness connector M49 (A) terminal 20.

      4 - 20: Continuity should exist  .

    Fig 5: Checking Continuity Between Front Air Control And Unified Meter And A/C Amp. Connector Terminal
    G04917636Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: Replace front air control. Refer to "CENTER STACK ASSEMBLY ".

    NG: Repair harness or connector.

scientia non olet · About LEMON Manuals