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Home >> Infiniti >> 2005 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P1572: ASCD Brake Switch >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK OVERALL FUNCTION-I 

    With CONSULT-II 

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

      CONDITION INDICATION
      Brake pedal: Slightly depressed OFF
      Brake pedal: Fully released ON
      Fig 1: CONSULT-II Display - "BRAKE SW1" In "DATA MONITOR" Mode
      G02389312Courtesy of NISSAN MOTOR CO., U.S.A.

      Without CONSULT-II 

      1. Turn ignition switch ON.
      2. Check voltage between ECM terminal 108 and ground under the following conditions.
        BRAKE SWITCH 1 CONDITION - VOLTAGE

        CONDITION VOLTAGE
        Brake pedal: Slightly depressed Approximately 0V
        Brake pedal: Fully released Battery voltage
        Fig 2: Checking Voltage Between ECM Terminal 108 And Ground
        G02389313Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      1. OK: GO TO 2.
      2. NG: GO TO  5.
    4. CHECK OVERALL FUNCTION-II 

      With CONSULT-II 

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

      BRAKE SWITCH 2 CONDITION - INDICATION

      CONDITION INDICATION
      Brake pedal: Fully released OFF
      Brake pedal: Slightly depressed ON
      Fig 3: CONSULT-II Display - "BRAKE SW2" In "DATA MONITOR" Mode
      G02389314Courtesy of NISSAN MOTOR CO., U.S.A.

      Without CONSULT-II 

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

      BRAKE SWITCH 2 CONDITION - VOLTAGE

      CONDITION VOLTAGE
      Brake pedal: Fully released Approximately 0V
      Brake pedal: Slightly depressed Battery voltage
      Fig 4: Checking Voltage Between ECM Terminal 101 And Ground
      G02389315Courtesy of NISSAN MOTOR CO., U.S.A.

      OK or NG 

      1. OK: GO TO  9.
      2. NG: GO TO  5.
    5. 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 5: Identifying ASCD Brake Switch, Stop Lamp Switch & Brake Pedal
        G02389316Courtesy of NISSAN MOTOR CO., U.S.A.
      4. Check voltage between ASCD brake switch terminal 1 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  3.
    2. NG: GO TO 4.
    Fig 6: Checking Voltage Between ASCD Brake Switch Terminal 1 & Ground
    G02389317Courtesy of NISSAN MOTOR CO., U.S.A.
  2. 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
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  3. 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 .

      1. Continuity should exist. 
    4. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 6.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  4. CHECK ASCD BRAKE SWITCH 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO  9.
    2. NG: Replace ASCD brake switch.
  5. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp switch harness connector.
      Fig 7: Identifying ASCD Brake Switch, Stop Lamp Switch & Brake Pedal
      G02389318Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between stop lamp switch terminal 3 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  7.
    2. NG: GO TO 8.
    Fig 8: Checking Voltage Between Stop Lamp Switch Terminal 3 & Ground
    G02389319Courtesy of NISSAN MOTOR CO., U.S.A.
  6. 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
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  7. 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 .

      1. Continuity should exist. 
    3. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 10.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  8. CHECK STOP LAMP SWITCH 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO 11.
    2. NG: Replace stop lamp switch.
  9. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. : INSPECTION END 
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