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Home >> Nissan-Datsun >> 2004 >> Quest SL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System >> 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.
      Fig 1: Checking Stop Lamp Condition
      G00775950Courtesy of NISSAN MOTOR CO., U.S.A.

    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 2: Disconnecting Stop Lamp Switch Harness Connector
      G00775951Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check voltage between stop lamp switch terminal 1 and ground with CONSULT-II or tester.
      Fig 3: Checking Voltage Between Stop Lamp Switch Terminal 1 And Ground
      G00775952Courtesy of NISSAN MOTOR CO., U.S.A.
      1. Voltage: Battery voltage

    OK or NG 

    1. OK: GO TO  6 .
    2. NG: GO TO 3.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • 10A fuse
    • Fuse block (J/B) connector E30
    • Harness for open and short between stop lamp switch and fuse
      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. Turn ignition switch OFF.
    2. Disconnect ECM 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 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 toCOMPONENT 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