2008 Lexus IS FFACTORY OEM SERVICE PROCEDURE

Inspection Procedure

NOTE:
  • When the front power window regulator motor assembly (for driver side) connector or the multiplex network master switch assembly connector is disconnected, the power window control system must be initialized (See CUSTOMIZE PARAMETERS  ).
  • Since the power window control system has functions that use multiplex communication (BEAN), first confirm that there is no malfunction in the multiplex communication system by inspecting the multiplex communication functions in accordance with the How to Proceed with Troubleshooting procedure (See HOW TO PROCEED WITH TROUBLESHOOTING  ). Then, conduct the following inspection procedure.
  1. CHECK FUSES (FR DOOR LH, ECU-IG RH and MPX-B) 
    1. Remove the FR DOOR LH fuse from the main body ECU LH (cowl side junction block LH)
    2. Remove the ECU-IG RH fuse from the main body ECU RH (cowl side junction block RH)
    3. Remove the MPX-B fuse from the engine room relay block No 1
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      FR DOOR LH fuse Always Below 1 Ω
      ECU-IG RH fuse Always Below 1 Ω
      MPX-B fuse Always Below 1 Ω

    NG: REPLACE FUSE 

    OK: Go to next step 

  2. PERFORM ACTIVE TEST USING TECHSTREAM (DRIVER SIDE POWER WINDOW UP/DOWN) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on
    4. Enter the following menus. Body Electrical / Master Switch / Active Test.
    5. Perform the Active Test according to the display on the Techstream.

      Master Switch (Multiplex Network Master Switch Assembly) 

      ACTIVE TEST

      Tester Display Test Part Control Range Diagnostic Note
      Driver Side Power Window Driver side power window UP/DOWN -

      OK: Driver side power window operates normally. 

      CAUTION: Be careful to avoid injuries as this test causes vehicle parts to move.
      During the Active Test, the jam protection function will not operate.

    NG: Go to step 3 

    OK: REPLACE MULTIPLEX NETWORK MASTER SWITCH ASSEMBLY  (See REMOVAL  )

  3. CHECK HARNESS AND CONNECTOR (MULTIPLEX NETWORK MASTER SWITCH - BODY GROUND AND BATTERY) 
    1. Disconnect the multiplex network master switch assembly connector
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      M7-2 (GND) - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.
      Fig 1: Identifying Multiplex Network Master Switch Assembly Connector
      G05755732Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage 

      STANDARD VOLTAGE

      Tester Connection Condition Specified Condition
      M7-10 (BDR) - M7-2 (GND) Always 11 to 14 V
      M7-20 (SIG) - M7-2 (GND) Engine switch off Below 1 V
      M7-20 (SIG) - M7-2 (GND) Engine switch on (IG) 11 to 14 V

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. INSPECT FRONT POWER WINDOW REGULATOR MOTOR ASSEMBLY (for Driver Side) 
    1. Remove the front power window regulator motor assembly (for driver side) (See REMOVAL  ).
    2. Check power window regulator motor operation:
      1. Apply battery voltage to connector terminals 1 and 2
        NOTE: Do not apply battery voltage to any terminals except terminals 1 and 2.
      2. Check that the motor gear rotates smoothly as follows.

        OK 

        MEASUREMENT CONDITION AND SPECIFIED CONDITION

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Motor gear rotates counterclockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Motor gear rotates clockwise
    3. Check PTC operation
      Fig 2: Identifying Front Power Window Regulator Motor Assembly (For Driver Side)
      G05755733Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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