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Home >> Infiniti >> 2008 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P1148 To P2A03 >> DTC P1564: ASCD Steering Switch >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK GROUND CONNECTIONS
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 1: Identifying Body Ground Screw
      G05739635Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK ASCD STEERING SWITCH CIRCUIT

    With CONSULT-III 

    1. Turn ignition switch ON.
    2. Select "MAIN SW", "CANCEL SW", RESUME/ACC SW" and "SET SW" in "DATA MONITOR" mode with CONSULT-III.
    3. Check each item indication under the following conditions.
      MONITOR ITEM CONDITION CHART

      Switch Monitor item Condition Indication
      MAIN switch MAIN SW Pressed ON
      Released OFF
      CANCEL switch CANCEL SW Pressed ON
      Released OFF
      RESUME/ACCELERATE switch RESUME/ACC SW Pressed ON
      Released OFF
      SET/COAST switch SET SW Pressed ON
      Released OFF

    Without CONSULT-III 

    1. Turn ignition switch ON.
    2. Check voltage between ECM terminal 99 and ground with pressing each button.
      VOLTAGE REFERENCE CHART

      Switch Condition Voltage [V]
      MAIN switch Pressed Approx. 0
      Released Approx. 4
      CANCEL switch Pressed Approx. 1
      Released Approx. 4
      RESUME/ACCELERATE switch Pressed Approx. 3
      Released Approx. 4
      SET/COAST switch Pressed Approx. 2
      Released Approx. 4
      Fig 2: Checking Voltage Between ECM Terminal 99 And Ground
      G05739636Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  8.

    NG: GO TO 3.

  3. CHECK ASCD STEERING SWITCH GROUND CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect combination switch harness connector M102.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between combination switch terminal 15 and ECM terminal 67.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    5. Also check harness for short to ground and short to power.

    OK or NG 

    OK: GO TO  5.

    NG: GO TO 4.

    Fig 3: Identifying Combination Switch Harness Connector M102
    G05739637Courtesy of NISSAN MOTOR CO., U.S.A.
  4. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors M31, E152
    • Harness connectors E5, F14
    • Combination switch (spiral cable)
    • Harness for open and short between ECM and combination switch

      Repair open circuit or short to ground or short to power in harness or connectors.

  5. CHECK ASCD STEERING SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Check harness continuity between ECM terminal 99 and combination switch terminal 14.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    2. Also check harness for short to ground and short to power.

    OK or NG 

    OK: GO TO  7.

    NG: GO TO 6.

  6. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors M31, E152
    • Combination switch (spiral cable)
    • Harness for open and short between ECM and combination switch

      Repair open circuit or short to ground or short to power in harness or connectors.

  7. CHECK ASCD STEERING SWITCH

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 8.

    NG: Replace ASCD steering switch.

  8. CHECK INTERMITTENT INCIDENT

    Refer to "HOW TO CHECK TERMINAL " and "INTERMITTENT INCIDENT ".

    INSPECTION END 

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