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.
| Symptom | Suspected Area | Link |
|---|---|---|
| Both left and right low beam headlights do not illuminate. | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | | |
| Low beam headlight on right side does not illuminate. | Headlight unit assembly RH | |
| Headlight ECU sub-assembly RH | | |
| Low beam headlight on left side does not illuminate. | Headlight unit assembly LH | |
| Headlight ECU sub-assembly LH | | |
| Both left and right high beam headlights do not illuminate. | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | | |
| High beam headlight on right side does not illuminate. | Headlight unit assembly RH | |
| Headlight ECU sub-assembly RH | | |
| High beam headlight on left side does not illuminate. | Headlight unit assembly LH | |
| Headlight ECU sub-assembly LH | | |
| Both left and right side marker lights do not illuminate. | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | | |
| Side marker light on right side does not illuminate. | Headlight unit assembly RH | |
| Headlight ECU sub-assembly RH | | |
| Side marker light on left side does not illuminate. | Headlight unit assembly LH | |
| Headlight ECU sub-assembly LH | | |
| High beam flash function does not operate (high beam headlights are normal). | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | | |
| Low beam and high beam headlight on right side does not illuminate. | Power source circuit | |
| Headlight ECU sub-assembly RH | | |
| Low beam and high beam headlight on left side does not illuminate. | Power source circuit | |
| Headlight ECU sub-assembly LH | |
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| Symptom | Suspected Area | Link |
|---|---|---|
| Both left and right clearance lights do not illuminate. | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | | |
| Clearance light on right side does not illuminate. | Daytime running light relay circuit | |
| Headlight ECU sub-assembly RH | | |
| Clearance light on left side does not illuminate. | Daytime running light relay circuit | |
| Headlight ECU sub-assembly LH | |
| 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) | | |
| Daytime running light on right side does not illuminate. | Daytime running light relay circuit | |
| Headlight ECU sub-assembly RH | | |
| Daytime running light on left side does not illuminate. | Daytime running light relay circuit | |
| Headlight ECU sub-assembly LH | | |
| Clearance light and daytime running light on right side does not illuminate. | Power source circuit | |
| Daytime running light relay circuit | | |
| Headlight ECU sub-assembly RH | | |
| Clearance light and daytime running light on left side does not illuminate. | Power source circuit | |
| Daytime running light relay circuit | | |
| Headlight ECU sub-assembly LH | |
| Symptom | Suspected Area | Link |
|---|---|---|
| Both left and right front fog lights do not illuminate (taillight is normal). | Headlight dimmer switch circuit | |
| Front fog light circuit | | |
| Main body ECU (Multiplex network body ECU) | | |
| All of the front fog light does not illuminate. | Front fog light circuit | |
| Symptom | Suspected Area | Link |
|---|---|---|
| License plate light does not illuminate. | Harness or connector | - |
| License plate light assembly LH | | |
| License plate light assembly RH | |
| 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) | |
| 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. | STOP fuse | - |
| Harness or connector | - | |
| Stop light switch assembly | | |
| Stop light control assembly | |
| Symptom | Suspected Area | Link |
|---|---|---|
| All of the back-up lights do not operate. | BKUP LP fuse | - |
| 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 | - |
| 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 | |
| Symptom | Suspected Area | Link |
|---|---|---|
| Both left and right cornering lights do not illuminate. | Headlight dimmer switch circuit | |
| Combination meter assembly | | |
| Cornering light on right side does not illuminate. | Cornering light circuit | |
| Headlight ECU sub-assembly RH | | |
| Cornering light on left side does not illuminate. | Cornering light circuit | |
| Headlight ECU sub-assembly LH | |
| 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 | |
| Symptom | Suspected Area | Link |
|---|---|---|
| Automatic light control system does not operate. | Headlight dimmer switch circuit | |
| Main body ECU (Multiplex network body ECU) | |
| 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) | |
| 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) | |
| 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
Diagnosis System
DIAGNOSIS SYSTEM DESCRIPTION (a) Lighting system data and the Diagnostic Trouble Codes (DTCs) can be read from the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfunctioni
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
SEE MORE:
Precaution
PRECAUTION NOTICE: When disassembling the headlight assembly, use static electricity countermeasures SST (desktop antistatic mat set) and observe all precautions to prevent damage to the system by electrostatic discharge (ESD). STATIC ELECTRICITY COUNTERMEASURES SST SST:Desktop antistatic mat set (0
Disassembly
DISASSEMBLY CAUTION / NOTICE / HINT HINT:
Use the same procedure for the RH and LH sides.
The procedure listed below is for the LH side.
PROCEDURE 1. REMOVE NO. 3 MOULDING TAPE (a) Remove the No. 3 moulding tape. HINT: Do not pull on the No. 3 moulding tape. Instead, roll the tape up with y
