Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Problem Symptoms Table

Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual / Vehicle Exterior / Lighting (ext) / Lighting System (w/ Automatic Headlight Beam Level Control System) / Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
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If the No. 1 headlight ECU sub-assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the No. 1 headlight ECU sub-assembly LH.
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If the headlight assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the No. 1 headlight ECU sub-assembly LH.*
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When replacing the No. 1 headlight ECU sub-assembly LH, always replace it with a new one. If a No. 1 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 headlight assembly LH, always replace it with a new one. If a headlight 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.
- *: for TMMC Made

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	No. 1 headlight ECU sub-assembly LH
	Headlight unit LH*1
	Headlight assembly LH*2
Right low beam headlight does not illuminate	No. 1 headlight ECU sub-assembly RH
	Headlight unit RH*1
	Headlight assembly RH*2
Both left and right low beam headlights do not illuminate	Headlight dimmer switch circuit
Both left and right low beam headlights do not illuminate	Main body ECU (Multiplex network body ECU)
Left high beam headlight does not illuminate	High beam headlight circuit
Left high beam headlight does not illuminate	No. 1 headlight ECU sub-assembly LH
Right high beam headlight does not illuminate	High beam headlight circuit
Right high beam headlight does not illuminate	No. 1 headlight ECU sub-assembly RH
Both left and right high beam headlights do not illuminate	Headlight dimmer switch circuit
Both left and right high beam headlights do not illuminate	Main body ECU (Multiplex network body ECU)
High Flash (passing function) does not operate (high beam headlights are normal)	Headlight dimmer switch circuit
	Main body ECU (Multiplex network body ECU)
Left low beam headlight and high beam headlight do not illuminate	No. 1 headlight ECU sub-assembly LH
Right low beam headlight and high beam headlight do not illuminate	No. 1 headlight ECU sub-assembly RH
Left low beam headlight and high beam headlight flicker	No. 1 headlight ECU sub-assembly LH
Right low beam headlight and high beam headlight flicker	No. 1 headlight ECU sub-assembly RH

*1: for TMC Made
*2: for TMMC Made

Parking Light/Daytime Running Light

Symptom	Suspected Area	Link
Left parking light/daytime running light does not illuminate	Parking light/daytime running light circuit
	No. 1 headlight ECU sub-assembly LH
Right parking light/daytime running light does not illuminate	Parking light/daytime running light circuit
	No. 1 headlight ECU sub-assembly RH
Both left and right parking lights do not illuminate	Headlight dimmer switch circuit
Both left and right parking lights do not illuminate	Main body ECU (Multiplex network body ECU)
Both left and right daytime running lights do not illuminate	Check customize settings
	Headlight dimmer switch circuit
	Main body ECU (Multiplex network body ECU)
Left parking light/daytime running light flicker	No. 1 headlight ECU sub-assembly LH
Right parking light/daytime running light flicker	No. 1 headlight ECU sub-assembly RH

Cornering Light (w/ Front Fog Light)

Symptom	Suspected Area	Link
Left cornering light does not illuminate	Check operating conditions
	Cornering light circuit
	No. 1 headlight ECU sub-assembly LH
Right cornering light does not illuminate	Check operating conditions
	Cornering light circuit
	No. 1 headlight ECU sub-assembly RH
Left cornering light flicker	No. 1 headlight ECU sub-assembly LH
Right cornering light flicker	No. 1 headlight ECU sub-assembly RH

Front Side Marker Light (w/ Front Side Marker Light)

Symptom	Suspected Area	Link
Left front side marker light does not illuminate	Front side marker light circuit
Left front side marker light does not illuminate	No. 1 headlight ECU sub-assembly LH
Right front side marker light does not illuminate	Front side marker light circuit
Right front side marker light does not illuminate	No. 1 headlight ECU sub-assembly RH
Both left and right front side marker lights do not illuminate	Headlight dimmer switch circuit
	Main body ECU (Multiplex network body ECU)
Left front side marker light flicker	No. 1 headlight ECU sub-assembly LH
Right front side marker light flicker	No. 1 headlight ECU sub-assembly RH

Taillight

Symptom	Suspected Area	Link
Left or right taillight (rear combination light assembly) does not illuminate	Rear combination light assembly (w/ Rear No. 2 Seat)
	Rear combination light assembly (w/o Rear No. 2 Seat)
	Rear light cord (w/ Rear No. 2 Seat)*
	Rear light cord (w/o Rear No. 2 Seat)*
	Harness or connector	-
Left or right taillight (rear light assembly) does not illuminate	Rear light assembly
	Rear light socket and wire
	Harness or connector	-
All of the taillights, license plate lights and rear side marker lights do not illuminate	Headlight dimmer switch circuit
	Taillight relay circuit
	Main body ECU (Multiplex network body ECU)

*: for Bulb Type Turn Signal Light

Rear Side Marker Light

Symptom	Suspected Area	Link
Left or right rear side marker light does not illuminate	Rear combination light assembly (w/ Rear No. 2 Seat)
Left or right rear side marker light does not illuminate	Rear combination light assembly (w/o Rear No. 2 Seat)

License Plate Light

Symptom	Suspected Area	Link
License plate light does not illuminate	License plate light assembly
License plate light does not illuminate	Harness or connector	-

Stop Light

Symptom	Suspected Area	Link
Left or right stop light (rear combination light assembly) does not illuminate	Rear combination light assembly (w/ Rear No. 2 Seat)
	Rear combination light assembly (w/o Rear No. 2 Seat)
	Rear light cord (w/ Rear No. 2 Seat)*
	Rear light cord (w/o Rear No. 2 Seat)*
	Harness or connector	-
Left or right stop light (rear light assembly) does not illuminate	Rear light assembly
	Rear light socket and wire
	Harness or connector	-
All of the stop lights do not illuminate	STOP fuse	-
	Stop light switch assembly
	Semiconductor power integration ECU
	Harness or connector	-

*: for Bulb Type Turn Signal Light

High Mounted Stop Light

Symptom	Suspected Area	Link
High mounted stop light does not illuminate	Center stop light assembly
High mounted stop light does not illuminate	Harness or connector	-

Front Fog Light (w/ Front Fog Light)

Symptom	Suspected Area	Link
Left or right front fog light does not illuminate	Fog light assembly
Left or right front fog light does not illuminate	Harness or connector	-
Both left and right front fog lights do not illuminate	Headlight dimmer switch circuit
	Front fog light circuit
	Taillight relay circuit
	Main body ECU (Multiplex network body ECU)

Back-up Light

Symptom	Suspected Area	Link
Left or right back-up light does not illuminate	Rear light assembly*1
	Back-up light bulb*2
	Rear light socket and wire
	Harness or connector	-
Both left and right back-up lights do not illuminate	ECU-ACC fuse	-
	BKUP LP fuse	-
	Park/neutral position switch assembly (for U881E)
	Park/neutral position switch assembly (for U881F)
	Instrument panel junction block assembly
	Harness or connector	-

*1: for LED Type Back-up Light
*2: for Bulb Type Back-up Light

Turn Signal Light

Symptom	Suspected Area	Link
Left or right front turn signal light does not operate*1	No. 1 headlight ECU sub-assembly
	Headlight unit*3
	Headlight assembly*4
	Harness or connector	-
Left or right front turn signal light does not operate*2	Front turn signal light bulb
	Headlight unit*3
	Headlight assembly*4
	No. 1 headlight ECU sub-assembly
	Harness or connector	-
Left or right rear turn signal light does not operate*5	Rear combination light assembly (w/ Rear No. 2 Seat)
	Rear combination light assembly (w/o Rear No. 2 Seat)
	Rear light assembly
	Rear light socket and wire
	Harness or connector	-
	Turn signal light circuit
Left or right rear turn signal light does not operate*6	Rear turn signal light bulb
	Rear light cord (w/ Rear No. 2 Seat)
	Rear light cord (w/o Rear No. 2 Seat)
	Harness or connector	-
Left or right side turn signal light does not operate	Side turn signal light assembly
	Outer rear view mirror assembly
	Outer mirror control ECU assembly
	Harness or connector	-
Turn signal lights do not operate in one direction	Turn signal switch circuit
Turn signal lights do not operate in one direction	Meter/gauge system
All turn signal lights do not operate	Turn signal switch circuit
All turn signal lights do not operate	Combination meter assembly
All turn signal lights do not flash at the correct speed	Combination meter assembly

*1: for Multiple Beam Headlight
*2: for Single Beam Headlight
*3: for TMC Made
*4: for TMMC Made
*5: for LED Type Turn Signal Light
*6: for Bulb Type Turn Signal Light

Hazard Warning Signal Light

Symptom	Suspected Area	Link
Hazard warning signal lights do not operate (turn signal lights are normal)	Hazard warning switch circuit
	Combination meter assembly
Hazard warning signal switch do not flash	Harness or connector	-
	Hazard warning signal switch (radio receiver assembly)
	Combination meter assembly

Automatic Light Control System

Symptom	Suspected Area	Link
Automatic light control system does not operate	Headlight dimmer switch circuit
Automatic light control system does not operate	Main body ECU (Multiplex network body ECU)

Light Auto Turn-off System

Symptom	Suspected Area	Link
Light auto turn-off system does not operate	Headlight dimmer switch circuit
	IG signal circuit
	Door courtesy switch circuit
	Main body ECU (Multiplex network body ECU)

Remote Operation Function (w/ Telematics System)

Symptom	Suspected Area	Link
Lights do not operate using remote operation function (Lighting system is normal)	Telematics system

Wiper-linked Low Beam Headlight Control System

Symptom	Suspected Area	Link
Wiper-linked low beam headlight control system does not operate	Check customize settings
	Main body ECU (Multiplex network body ECU)

Outside Handle Foot Light Control

Symptom	Suspected Area	Link
All of the outside handle foot lights do not illuminate	Check customize settings
	Power door lock control system
	Wireless door lock control system
	Smart access system with push-button start (for entry function)
	Door unlock detection switch circuit
	Outside handle foot light circuit
	Main body ECU (Multiplex network body ECU)
Left or right outside handle foot light does not illuminate	Front door outside handle assembly
	Rear door outside handle assembly
	Harness or connector	-

Welcome Light Illumination Control

Symptom	Suspected Area	Link
Welcome light illumination control does not operate	Check customize settings
Welcome light illumination control does not operate	Main body ECU (Multiplex network body ECU)

Automatic Headlight Beam Level Control System

Symptom	Suspected Area	Link
Automatic headlight beam level control system does not operate (Left Headlight)	No. 1 headlight ECU sub-assembly LH
	Headlight unit LH*1
	Headlight assembly LH*2
Automatic headlight beam level control system does not operate (Right Headlight)	No. 1 headlight ECU sub-assembly RH
	Headlight unit RH*1
	Headlight assembly RH*2
Initialization cannot be performed	CAN communication system
Initialization cannot be performed	No. 1 headlight ECU sub-assembly LH

*1: for TMC Made
*2: for TMMC Made

AFS (w/ AFS)

Symptom	Suspected Area	Link
AFS control does not operate (Left Headlight)	No. 1 headlight ECU sub-assembly LH
	Headlight unit LH*1
	Headlight assembly LH*2
AFS control does not operate (Right Headlight)	No. 1 headlight ECU sub-assembly RH
	Headlight unit RH*1
	Headlight assembly RH*2

*1: for TMC Made
*2: for TMMC Made

Automatic High Beam System (w/ Automatic High Beam System)

Symptom	Suspected Area	Link
Automatic high beam system does not operate or automatic high beam indicator light does not illuminate (low beam headlights and high beam headlights are normal)	Front radar sensor system
	Check Data List (Front Recognition Camera High Temperature 2)
	Check automatic high beam indicator light
	Check Data List (Auto H Beam STS0)
	Perform Active Test (Automatic High Beam Indicator)
	Automatic high beam switch
	Harness or connector
	Combination meter assembly
	Forward recognition camera
	Main body ECU (Multiplex network body ECU)

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