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Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.

HINT

If "+B of GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTC B1272, repair the "+B or GND short malfunction of communication bus" DTCs first (See DTC B1214 SHORT TO B+ IN DOOR SYSTEM COMMUNICATION BUS MALFUNCTION; DTC B1215 SHORT TO GND IN DOOR SYSTEM COMMUNICATION BUS MALFUNCTION  ).

  1. INSPECT FUSE (FR P/SEAT LH, MPX-B) 
    1. Remove the FR P/SEAT LH fuse from the cowl side junction block LH.
    2. Remove the MPX-B fuse from the engine room relay block No 1.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      RESISTANCE REFERENCE

      Tester Connection Condition Specified Condition
      FR P/SEAT LH fuse Always Below 1 Ω
      MPX-B fuse Always Below 1 Ω

    NG: REPLACE FUSE (FR P/SEAT LH, MPX-B) 

    OK: Go to Next Step 

  2. CHECK HARNESS AND CONNECTOR (FRONT POWER SEAT SWITCH - BATTERY AND BODY GROUND) 
    1. Disconnect the U6 and U7 connector.
    2. Measure the voltage and resistance according to the value(s) in the table below.

      Standard Voltage 

      VOLTAGE SPECIFICATION

      Tester Connection Condition Specified Condition
      U6-5 (+B) - Body ground Always 11 to 14 V
      U7-8 (SYSB) - Body ground Always 11 to 14 V

      Standard Resistance 

      RESISTANCE REFERENCE

      Tester Connection Condition Specified Condition
      U6-1 (GND) - Body ground Always Below 1 Ω
      3. Fig 1: Identifying U6 And U7 Connector Terminal
      G05754063Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (FRONT POWER SEAT SWITCH - BATTERY AND BODY GROUND) 

    OK: Go to Next Step 

  3. CHECK HARNESS AND CONNECTOR (COMMUNICATION LINE) 
    1. Disconnect the U7, 2F and J55 connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      RESISTANCE REFERENCE

      Tester Connection Condition Specified Condition
      U7-1(MPX1) - 2F-5 (MPX1) or J55-24 (MPX2) Always Below 1 Ω
      3. Fig 2: Identifying U7, 2F And J55 Connector Terminal
      G05754064Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE FRONT POWER SEAT SWITCH LH  (See REMOVAL )

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