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Home >> Nissan-Datsun >> 2012 >> Quest LE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P1550 To P2A03 >> DTC P1572: ASCD Brake Switch >> Diagnosis Procedure

Diagnosis Procedure

  1. CHECK OVERALL FUNCTION-I

    With CONSULT 

    1. Turn ignition switch ON.
    2. Select "BRAKE SW1" in "DATA MONITOR" mode with CONSULT.
    3. Check "BRAKE SW1" indication under the following conditions.
      Monitor item Condition Indication
      BRAKE SW1 Brake pedal Slightly depressed OFF
      Fully released ON

    Without CONSULT 

    1. Turn ignition switch ON.
    2. Check the voltage between ECM harness connectors.
      ECM Condition Voltage
      Connector + -
      Terminal Terminal
      E16 126 (ASCD brake switch signal) 128 Brake pedal Slightly depressed Approx. 0 V
      Fully released Battery voltage

      Is the inspection result normal? 

      YES: GO TO 2.

      NO: GO TO  3.

  2. CHECK OVERALL FUNCTION-II

    With CONSULT 

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

    Monitor item Condition Indication
    BRAKE SW2 Brake pedal Slightly depressed ON
    Fully released OFF

    Without CONSULT 

    Check the voltage between ECM harness connectors.

    ECM Condition Voltage
    Connector + -
    Terminal Terminal
    E16 122 (Stop lamp switch signal) 128 Brake pedal Slightly depressed Battery voltage
    Fully released Approx. 0 V

    Is the inspection result normal? 

    YES: GO TO  16.

    NO: 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.
    4. Check the voltage between ASCD brake switch harness connector and ground.
      ASCD brake switch Ground Voltage
      Connector Terminal
      E109 1 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO  5.

      NO: GO TO 4.

  4. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103
    • 10 A fuse (No. 3)
    • Harness for open or short between ASCD brake switch and fuse

      : Repair open circuit, 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 the continuity between ASCD brake switch harness connector and ECM harness connector.
      ASCD brake switch ECM Continuity
      Connector Terminal Connector Terminal
      E109 2 E16 126 Existed
    4. Also check harness for short to ground and short to power.

      Is the inspection result normal? 

      YES: GO TO 6.

      NO: Repair open circuit, short to ground or short to power in harness or connectors.

  6. CHECK ASCD BRAKE SWITCH

    Refer to "COMPONENT INSPECTION (ASCD BRAKE SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO  9.

    NO: Replace ASCD brake switch. Refer to "EXPLODED VIEW ".

  7. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp switch harness connector.
    3. Check the voltage between stop lamp switch harness connector and ground.
      Stop lamp switch Ground Voltage
      Connector Terminal
      E115 1 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO  9.

      NO: GO TO 8.

  8. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103
    • 10 A fuse (No. 7)
    • Harness for open or short between stop lamp switch and battery

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

  9. CHECK STOP LAMP RELAY GROUND CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp relay harness connector.
    3. Check the continuity between stop lamp relay harness connector and ground.
      Stop lamp relay Ground Continuity
      Connector Terminal
      E15 1 Ground Existed

      Is the inspection result normal? 

      YES: GO TO 10.

      NO: Repair open circuit or short to ground or short to power in harness or connectors.

  10. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT
    1. Connect stop lamp switch harness connector.
    2. Turn ignition switch ON.
    3. Check the voltage between stop lamp relay harness connector and ground.
      Stop lamp relay Ground Condition Voltage (V)
      Connector Terminal
      E15 2 Ground Brake pedal Slightly depressed Battery voltage
      Fully released Approx. 0

      Is the inspection result normal? 

      YES: GO TO  12.

      NO: GO TO 11.

  11. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness for open or short between stop lamp switch and stop lamp relay

      Is the inspection result normal? 

      YES: GO TO  14.

      NO: Repair open circuit or short to ground or short to power in harness or connectors.

  12. CHECK STOP LAMP RELAY POWER SUPPLY CIRCUIT
    1. Check the voltage between stop lamp relay harness connector and ground.
      Stop lamp relay Ground Voltage (V)
      Connector Terminal
      E15 5 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO 13.

      NO: Repair open circuit or short to ground or short to power in harness or connectors.

  13. CHECK STOP LAMP RELAY INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp relay harness connector.
    3. Check the continuity between stop lamp relay harness connector and ECM harness connector.
      ECM Stop lamp relay Continuity
      Connector Terminal Connector Terminal
      E16 122 E15 3 Existed
    4. Also check harness for short to ground and short to power.

      Is the inspection result normal? 

      YES: GO TO  15.

      NO: Repair open circuit or short to ground or short to power in harness or connectors.

  14. CHECK STOP LAMP SWITCH

    Refer to "COMPONENT INSPECTION (STOP LAMP SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO  16.

    NO: Replace stop lamp switch.

  15. CHECK STOP LAMP RELAY

    Refer to "COMPONENT INSPECTION (STOP LAMP RELAY) ".

    Is the inspection result normal? 

    YES: GO TO 16.

    NO: Replace stop lamp relay.

  16. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    : INSPECTION END

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