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Home >> Lexus >> 2015 >> NX 200t Base, FWD >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (Triple Beam Headlight) - Diagnostic Codes & Symptom Tests >> LIGHTING SYSTEM (For Triple Beam Headlight) >> Power Source Circuit [10/2014 - 09/2017] >> Procedure

Power Source Circuit [10/2014 - 09/2017]: Procedure

  1. CHECK HARNESS AND CONNECTOR (HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY - BATTERY AND BODY GROUND) 
    1. Disconnect the A19 headlight light control ECU sub-assembly LH or A20 headlight light control ECU sub-assembly RH connector.
      GTY503685Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *A Headlight light control ECU sub-assembly LH
      *B Headlight light control ECU sub-assembly RH
      *a Front view of wire harness connector
      (Headlight light control ECU sub-assembly)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY LH

      Tester Connection Switch Condition Specified Condition
      A19-13 (ECUB) - Body ground Headlight on 11 to 14 V
      A19-4 (IG) - Body ground Engine switch on (IG) 11 to 14 V
      HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY RH

      Tester Connection Switch Condition Specified Condition
      A20-13 (ECUB) - Body ground Headlight on 11 to 14 V
      A20-4 (IG) - Body ground Engine switch on (IG) 11 to 14 V
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY LH

      Tester Connection Condition Specified Condition
      A19-12 (GND) - Body ground Always Below 1 Ω
      HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY RH

      Tester Connection Condition Specified Condition
      A20-12 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG (Headlight Light Control ECU Sub-assembly LH)
      NG (Headlight Light Control ECU Sub-assembly RH)

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2014 - 09/2017] 

    Result: 

    NG (Headlight Light Control ECU Sub-assembly RH) 

    See step  7

    Result: 

    NG (Headlight Light Control ECU Sub-assembly LH) 

    See step  2

  2. INSPECT HEADLIGHT DIMMER RELAY (H-LP LH/DIMMER [HI]) 
    1. Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.
    2. Inspect the headlight light dimmer relay (H-LP LH/DIMMER [HI]).

      Refer to ON-VEHICLE INSPECTION [10/2014 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HEADLIGHT DIMMER RELAY (H-LP LH/DIMMER [HI]) 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - BATTERY) 
    1. Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.
      GTY503635Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Headlight Light Dimmer Relay (H-LP LH/DIMMER) [HI]))
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      Relay terminal 1 - Body ground Always 11 to 14 V
      Relay terminal 5 - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY LH) 
    1. Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.
    2. Disconnect the A19 headlight light control ECU sub-assembly LH connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Relay terminal 3 - A19-13 (ECUB) Always Below 1 Ω
      Relay terminal 3 or A19-13 (ECUB) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU]) 
    1. Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.
    2. Remove the instrument panel junction block assembly.

      Refer to REMOVAL [10/2014 - 05/2019]

    3. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

      Refer to REMOVAL [10/2014 - 05/2019]

    4. Disconnect the 4B instrument panel junction block assembly connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Relay terminal 2 - A-15 (HRLY) Always Below 1 Ω
      Relay terminal 2 or A-15 (HRLY) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER RELAY [H-LP LH/DIMMER (HI)] - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) 
    1. Remove the headlight light dimmer relay (H-LP LH/DIMMER [HI]) from the engine room relay block.
    2. Disconnect the 4B instrument panel junction block assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Relay terminal 2 - 4B-53 Always Below 1 Ω
      Relay terminal 2 or 4B-53 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  7. CHECK HEADLIGHT RELAY (H-LP RH) 
    1. Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.
    2. Inspect the headlight light relay (H-LP RH).

      Refer to ON-VEHICLE INSPECTION [10/2014 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HEADLIGHT RELAY (H-LP RH RELAY) 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP RH] - BATTERY) 
    1. Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.
      GTY510430Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Headlight Relay [H-LP RH])
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      Relay terminal 1 - Body ground Always 11 to 14 V
      Relay terminal 5 - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP RH RELAY] - HEADLIGHT LIGHT CONTROL ECU ASSEMBLY RH AND MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU]) 
    1. Remove the headlight relay (H-LP RH) from the No. 2 engine room relay block.
    2. Disconnect the A20 headlight light control ECU sub-assembly LH connector.
    3. Disconnect the I48 main body ECU (multiplex network body ECU) connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      Relay terminal 3 - A20-13 (ECUB) Always Below 1 Ω
      Relay terminal 2 - I48-1 (DIM) Always Below 1 Ω
      Relay terminal 3 or A20-13 (ECUB) - Body ground Always 10 kΩ or higher
      Relay terminal 2 or I48-1 (DIM) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2014 - 05/2019] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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