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Driver Side Switch Module LIN Communication Malfunction: Procedure

  1. CLEAR DTC 
    1. Clear the DTC. Refer to DTC CHECK / CLEAR .

    NEXT: Go to next step 

  2. CHECK FOR DTC 
    1. Recheck for DTC. Refer to DTC CHECK / CLEAR .
      RESULT

      Result Proceed to
      DTC U1127, U1128* and U1129* are output A
      DTC U1127, U1128* or U1129* is output B
      No DTC is output C

      HINT: 

      *: w/ Climate Control Seat System

    C → See step   11 

    B → See step   10 

    A: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (OUTER MIRROR SWITCH - NO. 1 CONSOLE SWITCH) 
    1. Disconnect the L6 and L75 switch connectors.
      Fig 1: Identifying Terminals Of L6 And L75 Switch Connectors
      GTY116665Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance and voltage according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      L6-7 (MPX) - L75-3 (MPX) Always Below 1 Ω
      L6-7 (MPX) or L75-3 (MPX) - Body ground Always 10 kΩ or higher

      Standard voltage

      Tester Connection Condition Specified Condition
      L6-7 (MPX) or L75-3 (MPX) - Body ground Always Below 1 V

    NG → See step   4 

    OK → See step   12 

  4. CLEAR DTC 
    1. Reconnect the L6 switch connector.
    2. Clear the DTC. Refer to DTC CHECK / CLEAR .

    NEXT: Go to next step 

  5. CHECK FOR DTC 
    1. Disconnect the L75 switch connector.
    2. Recheck for DTC. Refer to DTC CHECK / CLEAR .
      RESULT

      Result Proceed to
      DTC U1127, U1128* and U1129* are output A
      DTC U1127 is output (w/o Rear Entertainment System) B
      DTC U1127 is output (w/ Rear Entertainment System) C

      HINT: 

      *: w/ Climate Control Seat System

    C → See step   16 

    B → See step   13 

    A: Go to next step 

  6. CLEAR DTC 
    1. Reconnect the L75 switch connector.
    2. Clear the DTC. Refer to DTC CHECK / CLEAR .

    NEXT: Go to next step 

  7. CHECK FOR DTC 
    1. Disconnect the e4 ECU connector.
    2. Recheck for DTC. Refer to DTC CHECK / CLEAR .
      RESULT

      Result Proceed to
      DTC U1127, U1128* and U1129* are output A
      DTC U1128* is output B

      HINT: 

      *: w/ Climate Control Seat System

    B → See step   14 

    A: Go to next step 

  8. CLEAR DTC 
    1. Reconnect the e4 ECU connector.
    2. Clear the DTC. Refer to DTC CHECK / CLEAR .

    NEXT: Go to next step 

  9. CHECK FOR DTC 
    1. Disconnect the e34 ECU connector.
    2. Recheck for DTC. Refer to DTC CHECK / CLEAR .
      RESULT

      Result Proceed to
      DTC U1127, U1128* and U1129* are output A
      DTC U1129* is output B

      HINT: 

      *: w/ Climate Control Seat System

    B → See step   15 

    A → REPAIR OR REPLACE HARNESS OR CONNECTOR 

  10. Go to DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  11. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  12. REPLACE OUTER MIRROR SWITCH. Refer to  REMOVAL 
  13. REPLACE NO. 1 CONSOLE SWITCH. Refer to  DISASSEMBLY 
  14. REPLACE FRONT SEAT CLIMATE CONTROL ECU RH. Refer to  DISASSEMBLY 
  15. REPLACE FRONT SEAT CLIMATE CONTROL ECU LH. Refer to  DISASSEMBLY 
  16. REPLACE NO. 1 CONSOLE SWITCH. Refer to  DISASSEMBLY 
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