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Home >> Infiniti >> 2013 >> M56 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P1087 To P2542 >> DTC P1805: Brake Switch >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK STOP LAMP SWITCH CIRCUIT 
    1. Turn ignition switch OFF.
    2. Check for stop lamp illumination under the following conditions.
      Condition Stop lamp
      Brake pedal Fully released Not illuminated
      Slightly depressed Illuminated

      Is the inspection result normal? 

      YES: GO TO  4.

      NO: GO TO 2.

  2. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT 
    1. Disconnect stop lamp switch harness connector.
    2. Check the voltage between stop lamp switch harness connector and ground.
      Stop lamp switch Ground Voltage
      Connector Terminal
      E110 1 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO  4.

      NO: GO TO 3.

  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • 10 A fuse (No. 7)
    • Harness for open or short between stop lamp switch and battery
    • Loose or poor connection for each connector and harness

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

  4. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Disconnect stop lamp switch harness connector.
    2. Disconnect ECM harness connector.
    3. Check the continuity between stop lamp switch harness connector and ECM harness connector.
      Stop lamp switch ECM Continuity
      Connector Terminal Connector Terminal
      E110 2 M160 158 Existed
    4. Also check harness for short to ground and short to power.

      Is the inspection result normal? 

      YES: GO TO  6.

      NO: GO TO 5.

  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness for open or short between ECM and stop lamp switch
    • Loose or poor connection for each connector and harness

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

  6. CHECK STOP LAMP SWITCH 

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

    Is the inspection result normal? 

    YES: GO TO 7.

    NO: Replace stop lamp switch. Refer to "EXPLODED VIEW ".

  7. CHECK INTERMITTENT INCIDENT 

    Refer to "INTERMITTENT INCIDENT ".

    : INSPECTION END