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Home >> Infiniti >> 2009 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Component Testing >> ASCD Brake Switch >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK OVERALL FUNCTION-I

    With CONSULT-III 

    1. Turn ignition switch ON.
    2. Select "BRAKE SW1" in "DATA MONITOR" mode with CONSULT-III.
    3. Check "BRAKE SW1" indication under the following conditions.
      BRAKE SWITCH INDICATION CONDITION

      CONDITION INDICATION
      Brake pedal: Slightly depressed OFF
      Brake pedal: Fully released ON

    Without CONSULT-III 

    1. Turn ignition switch ON.
    2. Check voltage between ECM terminal 108 and ground under the following conditions.
      VOLTAGE REFERENCE CHART

      CONDITION VOLTAGE
      Brake pedal: Slightly depressed Approximately 0V
      Brake pedal: Fully released Battery voltage
      Fig 1: Checking Voltage Between ECM Terminal 108 And Ground
      G06315829Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      OK: GO TO 2.

      NG: GO TO  3.

  2. CHECK OVERALL FUNCTION-II

    With CONSULT-III 

    Check "BRAKE SW2" indication in "DATA MONITOR" mode.

    BRAKE SWITCH INDICATION CONDITION

    CONDITION INDICATION
    Brake pedal: Fully released OFF
    Brake pedal: Slightly depressed ON

    Without CONSULT-III 

    Check voltage between ECM terminal 101 and ground under the following conditions.

    VOLTAGE REFERENCE CHART

    CONDITION VOLTAGE
    Brake pedal: Fully released Approximately 0V
    Brake pedal: Slightly depressed Battery voltage
    Fig 2: Checking Voltage Between ECM Terminal 101 And Ground
    G06315830Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: INSPECTION END 

    NG: GO TO  7.

  3. CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect ASCD brake switch harness connector.
    3. Turn ignition switch ON.
      Fig 3: Identifying ASCD Brake And Stop Lamp Switch
      G06315831Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between ASCD brake switch terminal 1 and ground with CONSULT-III or tester.

      Voltage: Battery voltage 

      OK or NG 

      OK: GO TO  5.

      NG: GO TO 4.

      Fig 4: Checking Voltage Between ASCD Brake Switch Terminal 1 And Ground
      G06315832Courtesy of NISSAN MOTOR CO., U.S.A.
  4. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors M31, E152
    • Fuse block (J/B) connector M4
    • 10A fuse
    • Harness for open or short between ASCD brake switch and fuse

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

  5. CHECK ASCD BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminal 108 and ASCD brake switch terminal 2.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

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

      OK or NG 

      OK: GO TO 6.

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

  6. CHECK ASCD BRAKE SWITCH

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO  11.

    NG: Replace ASCD brake switch.

  7. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp switch harness connector.
      Fig 5: Identifying ASCD Brake And Stop Lamp Switch
      G06315833Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between stop lamp switch terminal 3 and ground with CONSULT-III or tester.

      Voltage: Battery voltage 

      OK or NG 

      OK: GO TO  9.

      NG: GO TO 8.

      Fig 6: Checking Voltage Between Stop Lamp Switch Terminal 3 And Ground
      G06315834Courtesy of NISSAN MOTOR CO., U.S.A.
  8. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors M31, E152
    • Fuse block (J/B) connector M60
    • 10A fuse
    • Harness for open or short between stop lamp switch and battery

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

  9. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 4.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

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

      OK or NG 

      OK: GO TO 10.

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

  10. CHECK STOP LAMP SWITCH

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 11.

    NG: Replace stop lamp switch.

  11. CHECK INTERMITTENT INCIDENT

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

    INSPECTION END 

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