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Home >> Infiniti >> 2005 >> FX45 >> Repair and Diagnosis >> Engine Performance >> Engine Control System - VK45DE >> DTC P1805: Brake Switch >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK STOP LAMP SWITCH CIRCUIT 
    1. Turn ignition switch OFF.
    2. Check the stop lamp when depressing and releasing the brake pedal.
    BRAKE PEDAL AND STOP LAMP REFERENCE CHART

    Brake pedal Stop lamp
    Fully released Not illuminated
    Slightly depressed Illuminated

    OK or NG

    1. OK: GO TO  4 .
    2. NG: GO TO 2.
  2. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT 
    1. Disconnect stop lamp switch harness connector.
      Fig 1: Disconnecting Stop Lamp Switch Harness Connector
      G02358795Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between stop lamp switch terminal 1 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG

    1. OK: GO TO  4 .
    2. NG: GO TO 3.
    Fig 2: Checking Voltage Between Stop Lamp Switch Terminal 1 And Ground
    G02358796Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • 10A fuse
    • Fuse block (J/B) connector E201
    • Harness for open and short between stop lamp switch and battery
      1. : Repair open circuit or 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 ECM harness connector.
    2. Disconnect stop lamp switch harness connector.
    3. Check harness continuity between ECM terminal 101 and stop lamp 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: GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E211, M41
    • Harness for open or short between ECM and stop lamp switch
      1. : Repair open circuit or short to ground or short to power in harness or connectors.
  6. CHECK STOP LAMP SWITCH 

    Refer to "COMPONENT INSPECTION  ".

    OK or NG

    1. OK: GO TO 7.
    2. NG: Replace stop lamp switch.
  7. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  ".

    1. : INSPECTION END