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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System (W/ AFS) - Diagnostics - Introduction (1 Of 2) >> LIGHTING SYSTEM (w/ AFS) >> Problem Symptoms Table [11/2023 - ] >> Problem Symptoms Table [11/2023 - ]

Problem Symptoms Table [11/2023 - ]

NOTE:
  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

    for HV Model: Refer to REGISTRATION [11/2023 - ]

    for Gasoline Model: Refer to REGISTRATION [11/2023 - ]

  • If the headlight ECU sub-assembly LH or headlight assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the headlight ECU sub-assembly LH.

    Refer to REMOVAL [11/2023 - ]

  • When replacing the headlight ECU sub-assembly LH or headlight assembly LH, always replace it with a new one. If a headlight ECU sub-assembly LH which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.
  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

HINT: 

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.

HEADLIGHT

Symptom Suspected Area Link
Left low beam headlight does not illuminate Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Headlight assembly LH Refer to REMOVAL [11/2023 - ]
Right low beam headlight does not illuminate Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Headlight assembly RH Refer to REMOVAL [11/2023 - ]
Left low beam headlight does not turn off Harness or connector (Headlight ECU sub-assembly LH (HEDL terminal) - Main body ECU (Multiplex network body ECU) (DIM terminal)) -
Both left and right low beam headlights do not illuminate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
Left high beam headlight does not illuminate High beam headlight circuit Refer to High Beam Headlight Circuit [11/2023 - ]
Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Right high beam headlight does not illuminate High beam headlight circuit Refer to High Beam Headlight Circuit [11/2023 - ]
Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Both left and right high beam headlights do not illuminate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
High Flash (passing function) does not operate (high beam headlights are normal) Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
Left low beam headlight and high beam headlight do not illuminate Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Right low beam headlight and high beam headlight do not illuminate Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Left low beam headlight and high beam headlight flicker Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Right low beam headlight and high beam headlight flicker Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
PARKING LIGHT/DAYTIME RUNNING LIGHT

Symptom Suspected Area Link
Left parking light/daytime running light does not illuminate Parking light/daytime running light circuit Refer to Parking Light/Daytime Running Light Circuit [11/2023 - ]
Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Right parking light/daytime running light does not illuminate Parking light/daytime running light circuit Refer to Parking Light/Daytime Running Light Circuit [11/2023 - ]
Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Both left and right parking lights do not illuminate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
Both left and right daytime running lights do not illuminate Check customize settings* Refer to CUSTOMIZE PARAMETERS [11/2023 - ] 
Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
Left parking light/daytime running light flicker Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Right parking light/daytime running light flicker Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
  1. *: for vehicles with customize setting "DRL Function"
FRONT SIDE MARKER LIGHT

Symptom Suspected Area Link
Left or right front side marker light does not illuminate Front side marker light bulb Refer to REPLACEMENT [12/2019 - ]
Harness or connector -
Both left and right front side marker lights do not illuminate Taillight relay circuit Refer to Taillight Relay Circuit [11/2023 - ]
Harness or connector -
FRONT FOG LIGHT

Symptom Suspected Area Link
Left or right front fog light does not illuminate Fog light assembly Refer to INSPECTION [09/2020 - ]
Harness or connector -
Both left and right front fog lights do not illuminate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Front fog light circuit Refer to Front Fog Light Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
TAILLIGHT

Symptom Suspected Area Link
Left or right taillight (rear combination light assembly) does not illuminate Rear combination light assembly Refer to INSPECTION [12/2019 - ]
Harness or connector -
Left or right taillight (rear light assembly) does not illuminate Rear light assembly Refer to INSPECTION [12/2019 - ]
Harness or connector -
All of the taillights, license plate lights and rear side marker lights do not illuminate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Taillight relay circuit Refer to Taillight Relay Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
REAR SIDE MARKER LIGHT

Symptom Suspected Area Link
Left or right rear side marker light does not illuminate Rear combination light assembly Refer to INSPECTION [12/2019 - ]
LICENSE PLATE LIGHT

Symptom Suspected Area Link
Left or right license plate light does not illuminate License plate light bulb Refer to REPLACEMENT [12/2019 - ]
Harness or connector -
License plate light assembly Refer to REMOVAL [12/2019 - ]
Both left and right license plate lights do not illuminate Taillight relay circuit Refer to Taillight Relay Circuit [11/2023 - ]
Harness or connector -
STOP LIGHT

Symptom Suspected Area Link
Left or right stop light does not illuminate Rear combination light assembly Refer to INSPECTION [12/2019 - ]
Harness or connector -
All of the stop lights do not illuminate STOP fuse -
Stop light switch assembly Refer to ON-VEHICLE INSPECTION [12/2019 - ]
Harness or connector -
HIGH MOUNTED STOP LIGHT

Symptom Suspected Area Link
High mounted stop light does not illuminate Center stop light assembly Refer to INSPECTION [12/2019 - ]
Harness or connector -
BACK-UP LIGHT

Symptom Suspected Area Link
Left or right back-up light does not illuminate Back-up light bulb Refer to REPLACEMENT [12/2019 - ]
Rear light assembly Refer to REMOVAL [12/2019 - ]
Harness or connector -
Both left and right back-up lights do not illuminate*1 Back-up light circuit Refer to Back-up Light Circuit [11/2023 - ]
Both left and right back-up lights do not illuminate*2 BKUP LP fuse -
ECU-ACC fuse -
Park/neutral position switch assembly Refer to INSPECTION [10/2022 - ]
Power distribution box assembly Refer to REMOVAL [11/2023 - ]
Harness or connector -
  1. *1: for HV Model
  2. *2: for Gasoline Model
TURN SIGNAL LIGHT

Symptom Suspected Area Link
Left or right front turn signal light does not operate Front turn signal light bulb Refer to REPLACEMENT [12/2019 - ]
Headlight assembly Refer to REMOVAL [11/2023 - ]
Harness or connector -
Left or right rear turn signal light does not operate Rear turn signal light bulb Refer to REPLACEMENT [12/2019 - ]
Rear combination light assembly Refer to REMOVAL [11/2023 - ]
Harness or connector -
Left or right side turn signal light does not operate Side turn signal light assembly Refer to INSPECTION [12/2019 - ]
Outer rear view mirror assembly Refer to REMOVAL [11/2023 - ]
Outer mirror control ECU assembly Refer to REMOVAL [12/2019 - ]
Harness or connector -
Turn signal lights do not operate in one direction Turn signal switch circuit Refer to Turn Signal Switch Circuit [12/2019 - ]
Meter/gauge system for 12.3 Inch Display: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - ]
except 12.3 Inch Display: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ]
All turn signal lights do not operate Turn signal switch circuit Refer to Turn Signal Switch Circuit [12/2019 - ]
Combination meter assembly Refer to REMOVAL [12/2019 - ]
All turn signal lights do not flash at the correct speed Combination meter assembly Refer to REMOVAL [12/2019 - ]
HAZARD WARNING SIGNAL LIGHT

Symptom Suspected Area Link
Hazard warning signal lights do not operate Hazard warning switch circuit Refer to Hazard Warning Switch Circuit [10/2022 - ]
Combination meter assembly Refer to REMOVAL [12/2019 - ]
DOOR MIRROR FOOT LIGHT

Symptom Suspected Area Link
Left or right door mirror foot light does not illuminate Door mirror foot light circuit Refer to Door Mirror Foot Light Circuit [11/2023 - ]
Outer mirror control ECU assembly Refer to REMOVAL [12/2019 - ]
Both left and right door mirror foot lights do not illuminate Check customize settings Refer to CUSTOMIZE PARAMETERS [11/2023 - ] 
Power door lock control system Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]
Wireless door lock control system Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]
Smart key system (for entry function) Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]
Door unlock detection switch circuit Refer to Door Unlock Detection Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
AUTOMATIC LIGHT CONTROL SYSTEM

Symptom Suspected Area Link
Automatic light control system does not operate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
LIGHT AUTO TURN-OFF SYSTEM

Symptom Suspected Area Link
Light auto turn-off system does not operate Headlight dimmer switch circuit Refer to Headlight Dimmer Switch Circuit [11/2023 - ]
IG signal circuit Refer to IG Signal Circuit [11/2023 - ]
Front door courtesy switch circuit Refer to Front Door Courtesy Switch Circuit [11/2023 - ]
Rear door courtesy switch circuit Refer to Rear Door Courtesy Switch Circuit [11/2023 - ]
Back door courtesy switch circuit Refer to Back Door Courtesy Switch Circuit [11/2023 - ]
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
REMOTE OPERATION FUNCTION (W/ TELEMATICS SYSTEM)

Symptom Suspected Area Link
Lights do not operate using remote operation function (Lighting system is normal) Telematics system Refer to HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ]
WIPER-LINKED LOW BEAM HEADLIGHT CONTROL SYSTEM

Symptom Suspected Area Link
Wiper-linked low beam headlight control system does not operate Check customize settings Refer to CUSTOMIZE PARAMETERS [11/2023 - ] 
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
WELCOME LIGHT ILLUMINATION CONTROL

Symptom Suspected Area Link
Welcome light illumination control does not operate Check customize settings Refer to CUSTOMIZE PARAMETERS [11/2023 - ] 
Main body ECU (Multiplex network body ECU) Refer to REMOVAL [11/2023 - ]
AUTOMATIC HEADLIGHT BEAM LEVEL CONTROL SYSTEM

Symptom Suspected Area Link
Automatic headlight beam level control system does not operate (Left Headlight) Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Headlight assembly LH Refer to REMOVAL [11/2023 - ]
Automatic headlight beam level control system does not operate (Right Headlight) Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Headlight assembly RH Refer to REMOVAL [11/2023 - ]
Initialization cannot be performed CAN communication system for HV Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]
for Gasoline Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]
Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
AFS

Symptom Suspected Area Link
AFS control does not operate (Left Headlight) Headlight ECU sub-assembly LH Refer to REMOVAL [11/2023 - ]
Headlight assembly LH Refer to REMOVAL [11/2023 - ]
AFS control does not operate (Right Headlight) Headlight ECU sub-assembly RH Refer to REMOVAL [11/2023 - ]
Headlight assembly RH Refer to REMOVAL [11/2023 - ]
AUTOMATIC HIGH BEAM SYSTEM

Symptom Suspected Area Link
Automatic high beam system does not operate or automatic high beam indicator does not illuminate (low beam headlights and high beam headlights are normal) Front radar sensor system Refer to Automatic High Beam System does not Operate or Operation Indicator does not Illuminate [11/2023 - ]
Check Data List (Front Recognition Camera High Temperature 2)
Check automatic high beam indicator light
Check Data List (Automatic High Beam Headlights Sensor Detection Status)
Perform Active Test (Multi Display All (White))
Auto high beam switch
Harness or connector
Combination meter assembly
Forward recognition camera
Main body ECU (Multiplex network body ECU)
Auto high beam switch indicator does not come ON Refer to "Automatic High Beam Switch Indicator does not Come ON" Refer to Automatic High Beam Switch Indicator does not Come ON [11/2023 - ]
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