Lexus NX: Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

  • Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.
  • 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.
  • Inspect the fuses related to this system before inspecting the suspected areas below.
Headlight

Symptom

Suspected Area

Link

One low beam headlight does not illuminate.

Harness or connector

-

Headlight assembly

Both left and right low beam headlights do not illuminate.

Headlight relay (H-LP [LO])

Headlight dimmer switch circuit

Low beam headlight circuit

Main body ECU (Multiplex network body ECU)

One high beam headlight does not illuminate.

Harness or connector

-

Headlight assembly

Both left and right high beam headlights do not illuminate.

Headlight dimmer relay (H-LP LH/DIMMER [HI])

Headlight dimmer switch circuit

High beam headlight circuit

Main body ECU (Multiplex network body ECU)

High beam flash function does not operate (high beam headlights are normal).

Headlight dimmer switch circuit

Main body ECU (Multiplex network body ECU)

One front side marker light does not illuminate.

Headlight assembly

Harness or connector

-

Both left and right side marker lights do not illuminate.

Harness or connector

-

Instrument panel junction block assembly

Side Marker Light

Symptom

Suspected Area

Link

One side marker light does not illuminate.

Headlight assembly

Harness or connector

-

Clearance Light

Symptom

Suspected Area

Link

One clearance light on right side does not illuminate.

Clearance light assembly

Harness or connector

-

Daytime Running Light

Symptom

Suspected Area

Link

Both left and right daytime running lights do not illuminate.

Headlight dimmer switch circuit

Main body ECU (Multiplex network body ECU)

Harness or connector

-

One daytime running light does not illuminate.

Daytime running light relay circuit

Harness or connector

-

One clearance light and daytime running light does not illuminate.

Daytime running light relay circuit

Harness or connector

-

Front Fog Light

Symptom

Suspected Area

Link

Both front fog lights do not illuminate (taillight is normal).

Headlight dimmer switch circuit

Front fog light circuit

Main body ECU (Multiplex network body ECU)

License Plate Light

Symptom

Suspected Area

Link

License plate light does not illuminate.

Harness or connector

-

License plate light assembly LH

License plate light assembly RH

Taillight

Symptom

Suspected Area

Link

Taillight (rear combination light assembly) does not illuminate.

Rear combination light socket and wire sub-assembly

Rear combination light assembly

Harness or connector

-

Instrument panel junction block assembly

Taillight (rear light assembly) does not illuminate.

Rear light assembly

Harness or connector

-

Instrument panel junction block assembly

All of the taillights do not illuminate

Headlight dimmer switch circuit

Taillight relay circuit

Main body ECU (Multiplex network body ECU)

Stop Light System

Symptom

Suspected Area

Link

Stop light (rear combination light assembly) on one side does not illuminate.

Rear combination light socket and wire sub-assembly

Rear combination light assembly

Harness or connector

-

Stop light (rear light assembly) on one side does not illuminate.

Rear light assembly

Harness or connector

-

Center stop light does not illuminate.

Center stop light assembly

Harness or connector

-

All of the stop lights do not operate.

Harness or connector

-

Stop light switch assembly

Stop light control ECU assembly

Back-up Light

Symptom

Suspected Area

Link

All of the back-up lights do not operate.

Harness or connector

-

Instrument panel junction block assembly [BKUP LP relay]

Hybrid vehicle control ECU

Back-up light on one side does not illuminate.

Rear light assembly

Harness or connector

-

Turn Signal Light

Symptom

Suspected Area

Link

No turn signal lights operate (hazard warning lights are normal).

Turn signal switch circuit

Combination meter assembly

One of the turn signal lights does not operate.

Meter/gauge system

Hazard Warning Light System

Symptom

Suspected Area

Link

Hazard warning lights do not operate (turn signal lights are normal).

Harness or connector

-

Hazard warning switch circuit

Combination meter assembly

Automatic Light Control System

Symptom

Suspected Area

Link

Automatic light control system does not operate.

Headlight dimmer switch circuit

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

Door courtesy switch circuit

IG signal circuit

Main body ECU (Multiplex network body ECU)

Welcome Light Illumination Control

Symptom

Suspected Area

Link

Welcome light illumination control does not operate.

Wireless door lock control system

Headlight dimmer switch circuit

Main body ECU (Multiplex network body ECU)

Lexus Enform Remote Services

Symptom

Suspected Area

Link

Lexus Enform Remote does not operate (lighting system is normal).

Telematics system

READ NEXT:

 Terminals Of Ecu

TERMINALS OF ECU CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY, MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) (a) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction

 Dtc Check / Clear

DTC CHECK / CLEAR CHECK FOR DTC (a) Connect the Techstream to the DLC3. (b) Turn the power switch on (IG). (c) Turn the Techstream on. (d) Enter the following menus: Body Electrical / Main body / Trou

 Freeze Frame Data

FREEZE FRAME DATA FREEZE FRAME DATA (a) Whenever a lighting system DTC is stored, the forward recognition camera stores the current vehicle state as freeze frame data. CHECK FREEZE FRAME DATA (a) Conn

SEE MORE:

 Open / Short in Steering Lock ECU (B2781)

DESCRIPTION The steering lock ECU and steering lock motor are built into the steering lock actuator assembly. The steering lock ECU (steering lock actuator assembly) detects whether the steering lock is in the lock or unlock position by using the lock sensor and unlock sensor of the steering lock mo

 Data List / Active Test

DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the following table, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not. HINT: Using the Techstream to read the Data List allows the values or state

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