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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (Ext) - Symptom Tests & Circuit Tests (2 Of 2) (Coupe) >> Lighting System >> Taillight Circuit [03/2017 - 04/2020] >> Procedure

Taillight Circuit [03/2017 - 04/2020]: Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Using the Techstream, perform the Active Test.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Main Body > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Taillight Relay Taillights, front side marker lights, rear side marker lights and license plate light OFF or ON -

      Body Electrical > Main Body > Active Test 

      Tester Display
      Taillight Relay

      OK

      Taillights, front side marker lights, rear side marker lights and license plate light illuminate.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [03/2017 - 05/2023] 

    Result: 

    NG 

    See step  2

  2. READ VALUE USING TECHSTREAM 
    1. Turn the light control switch tail position.
    2. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  3

  3. READ VALUE USING TECHSTREAM 
    1. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Tail Input Signal Light control switch tail position input signal OFF or ON OFF: Light control switch in neither tail nor head position
      ON: Light control switch in tail or head position      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Tail Input Signal

      OK

      Display changes according to the light control switch operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  4

  4. READ VALUE USING TECHSTREAM 
    1. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Tail Light No. 1 Output Signal Taillight output OFF or ON OFF: Taillight not illuminated
      ON: Taillight illuminated      		 Taillights blink while welcome light is operating

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Tail Light No. 1 Output Signal

      OK

      Display changes according to the light control switch operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (TAILLIGHT CIRCUIT) 
    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the X99 No. 3 semiconductor power integration ECU connector.
    3. Disconnect the D8 front marker light assembly LH connector.
    4. Disconnect the D7 front marker light assembly RH connector.
    5. Disconnect the X70 rear combination light lens and body LH connector.
    6. Disconnect the X69 rear combination light lens and body RH connector.
    7. Disconnect the c5 license plate light sub-assembly connector.
    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      X99-16 (L) - D8-1 (B) Always Below 1 Ω
    9. Connect the cable to the negative (-) battery terminal.
      NOTE:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected.

      Refer to INITIALIZATION [03/2017 - 04/2020]

    10. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      X99-16 (L) or D8-1 (B) - Body ground Always Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK FRONT MARKER LIGHT ASSEMBLY LH 
    1. Disconnect the D8 front marker light assembly LH connector.
    2. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    3. Turn the light control switch tail position.
    4. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT MARKER LIGHT ASSEMBLY LH. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    See step  7

  7. CHECK FRONT MARKER LIGHT ASSEMBLY RH 
    1. Disconnect the D7 front marker light assembly RH connector.
    2. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    3. Turn the light control switch tail position.
    4. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT MARKER LIGHT ASSEMBLY RH. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    See step  8

  8. CHECK REAR COMBINATION LIGHT LENS AND BODY LH 
    1. Disconnect the X70 rear combination light lens and body LH connector.
    2. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    3. Turn the light control switch tail position.
    4. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  9

  9. CHECK REAR COMBINATION LIGHT LENS LH 
    1. Remove the rear combination light lens LH.

      Refer to REMOVAL [03/2017 - ]

    2. Connect the X70 rear combination light lens and body LH connector.
    3. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    4. Turn the light control switch tail position.
    5. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT LENS LH. Refer to  REMOVAL [03/2017 - ] 

    Result: 

    NG 

    REPLACE REAR COMBINATION LIGHT LENS AND BODY LH. Refer to  DISASSEMBLY [03/2017 - ] 

  10. CHECK REAR COMBINATION LIGHT LENS AND BODY RH 
    1. Disconnect the X69 rear combination light lens and body RH connector.
    2. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    3. Turn the light control switch tail position.
    4. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  11

  11. CHECK REAR COMBINATION LIGHT LENS RH 
    1. Remove the rear combination light lens RH.

      Refer to REMOVAL [03/2017 - ]

    2. Disconnect the X69 rear combination light lens and body RH connector.
    3. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    4. Turn the light control switch tail position.
    5. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR COMBINATION LIGHT LENS RH. Refer to  REMOVAL [03/2017 - ] 

    Result: 

    NG 

    REPLACE REAR COMBINATION LIGHT LENS AND BODY RH. Refer to  DISASSEMBLY [03/2017 - ] 

  12. CHECK LICENSE PLATE LIGHT SUB-ASSEMBLY 
    1. Disconnect the c5 license plate light sub-assembly connector.
    2. Turn the light control switch off*1 or DRL off*2 position.
      1. *1: w/o DRL OFF Switch
      2. *2: w/ DRL OFF Switch
    3. Turn the light control switch tail position.
    4. Using the Techstream, read the Data List.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020]

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Status of Tail Light No. 1 Fuse Taillight fuse Connect or Disconnect Connect: Fuse not shut off
      Disconnect: Fuse shut off      		 -

      Body Electrical > Power Integration No. 3 > Data List 

      Tester Display
      Status of Tail Light No. 1 Fuse

      OK

      The Data List value displays "Connect".

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE LICENSE PLATE LIGHT SUB-ASSEMBLY. Refer to  REMOVAL [03/2017 - ] 

    Result: 

    NG 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (TAILLIGHT CIRCUIT) 
    1. Disconnect the cable from the negative (-) battery terminal.
    2. Disconnect the X99 No. 3 semiconductor power integration ECU connector.
    3. Disconnect the D8 front marker light assembly LH connector.
    4. Disconnect the D7 front marker light assembly RH connector.
    5. Disconnect the X70 rear combination light lens and body LH connector.
    6. Disconnect the X69 rear combination light lens and body RH connector.
    7. Disconnect the c5 license plate light sub-assembly connector.
    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      X99-16 (L) or D8-1 (B) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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