Problem Symptoms Table
WARNING: This page is about a different car, the 2006 Lexus GS 430 and 2006 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Headlight and taillight system:
HEADLIGHT AND TAILLIGHT SYSTEM PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| "LO-beam" headlight does not illuminate | Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT |
| Headlight relay circuit | HEADLIGHT RELAY CIRCUIT | |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| "HI-beam" headlight does not illuminate | Headlight (HI-BEAM) circuit | HEADLIGHT (HI-BEAM) CIRCUIT |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| "Flash" headlight does not illuminate | Headlight (HI-BEAM) circuit | HEADLIGHT (HI-BEAM) CIRCUIT |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Headlight is dark | Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Headlight does not illuminate or has abnormal operation | Headlight relay circuit | HEADLIGHT RELAY CIRCUIT |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Taillight does not illuminate or has abnormal operation | Taillight circuit | TAILLIGHT CIRCUIT |
| Multiplex network rear ECU (Luggage room junction block ECU) | - | |
| Both left and right headlight do not illuminate | Headlight (HI-BEAM) circuit | HEADLIGHT (HI-BEAM) CIRCUIT |
| Headlight relay circuit | HEADLIGHT RELAY CIRCUIT | |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Engine room No. 2 relay block (Front controller) | - | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Headlight beam level control system does not operate | Headlight beam level control actuator circuit | HEADLIGHT BEAM LEVEL CONTROL ACTUATOR CIRCUIT |
| Height control sensor circuit | HEIGHT CONTROL SENSOR CIRCUIT | |
| Headlight beam level control ECU communication circuit | HEADLIGHT BEAM LEVEL CONTROL ECU COMMUNICATION CIRCUIT | |
| Headlight beam level control ECU power source circuit | HEADLIGHT BEAM LEVEL CONTROL ECU POWER SOURCE CIRCUIT | |
| Headlight beam level control ECU | - | |
| Cowl side Junction block ECU LH | - | |
| Skid control ECU with actuator | - |
Stop light system:
STOP LIGHT SYSTEM PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| Stop light system does not illuminate | Stop light circuit | STOP LIGHT CIRCUIT |
| Multiplex network rear ECU (Luggage room junction block ECU) | - | |
| Hi-mounted stop light does not illuminate | Stop light circuit | STOP LIGHT CIRCUIT |
| Multiplex network rear ECU (Luggage room junction block ECU) | - |
Fog light system:
FOG LIGHT SYSTEM PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| Fog light does not illuminate or has abnormal operation | Front fog light circuit | FRONT FOG LIGHT CIRCUIT |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Headlight signal circuit | HEADLIGHT SIGNAL CIRCUIT | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - |
Turn signal light system:
TURN SIGNAL LIGHT SYSTEM PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| Hazard warning light does not illuminate | Hazard warning switch circuit | HAZARD WARNING SWITCH CIRCUIT |
| Turn signal flasher | - | |
| Multi-display (Hazard warning switch) | - | |
| Turn signal light does not illuminate | Turn signal light circuit | TURN SIGNAL LIGHT CIRCUIT |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Cowl side Junction block ECU LH | - |
Interior light system:
INTERIOR LIGHT SYSTEM PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| Door courtesy light does not illuminate | Door courtesy switch circuit | DOOR COURTESY SWITCH CIRCUIT |
| Door courtesy light circuit | DOOR COURTESY LIGHT CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Multiplex network door ECU front LH (Driver side door ECU) | - | |
| Multiplex network door ECU front RH (Front passenger side door ECU) | - | |
| Multiplex network door ECU rear LH (Rear door LH) | - | |
| Multiplex network door ECU rear RH (Rear door RH) | - | |
| Luggage room light does not illuminate | Luggage room light circuit | LUGGAGE ROOM LIGHT CIRCUIT |
| Cowl side junction block ECU LH | - | |
| Room light does not illuminate | Room light circuit | ROOM LIGHT CIRCUIT |
| Map light assembly (Overhead junction block) | - | |
| Cowl side junction block ECU LH | - | |
| Step illumination does not illuminate | Step illumination circuit | STEP ILLUMINATION CIRCUIT |
| Door courtesy switch circuit | DOOR COURTESY SWITCH CIRCUIT | |
| Multiplex network body ECU (Cowl side junction block ECU RH) | - | |
| Inside handle illumination light does not illuminate | Inside handle illumination light circuit | INSIDE HANDLE ILLUMINATION LIGHT CIRCUIT |
| Door courtesy switch circuit | DOOR COURTESY SWITCH CIRCUIT | |
| Multiplex network door ECU front LH (Driver side door ECU) | - | |
| Multiplex network door ECU front RH (Front passenger side door ECU) | - | |
| Multiplex network door ECU rear LH (Rear door LH) | - | |
| Multiplex network door ECU rear RH (Rear door RH) | - |
Others:
OTHERS PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| Back-up light does not illuminate | Back-up light circuit | BACK-UP LIGHT CIRCUIT |
| Multiplex network rear ECU (Luggage room junction block ECU) | - | |
| License plate light does not illuminate | Taillight circuit | TAILLIGHT CIRCUIT |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - | |
| Multiplex network rear ECU (Luggage room junction block ECU) | - | |
| Clearance light does not illuminate | Taillight circuit | TAILLIGHT CIRCUIT |
| Light control switch circuit | LIGHT CONTROL SWITCH CIRCUIT | |
| Combination switch assembly (Windshield wiper assembly) | - | |
| Engine room No. 2 relay block (Front controller) | - |
AFS
AFS PROBLEM SYMPTOMS
| Symptom | Suspected area | See |
|---|---|---|
| AFS does not operate(*1) | AFS ECU power source circuit | AFS ECU POWER SOURCE CIRCUIT |
| AFS ECU | AFS PROBLEM SYMPTOMS | |
| Only one swivel motor is not initialized(*1) | Headlight assembly or swivel motor stuck(*2) | - |
| Headlight swivel motor malfunction | - | |
| AFS ECU | AFS PROBLEM SYMPTOMS | |
| Only swivel control does not operate or malfunctions | AFS ECU switch status(*3) | - |
| Steering control ECU | - | |
| Vehicle speed sensor malfunction | - | |
| BEAN communication malfunction | - | |
| Headlight swivel motor malfunction | - | |
| AFS ECU | AFS PROBLEM SYMPTOMS | |
| Swivel control and leveling control do not operate | Height control sensor malfunction | - |
| Headlight swivel motor malfunction | - | |
| AFS ECU | AFS PROBLEM SYMPTOMS | |
| AFS OFF indicator light does not come on | AFS OFF switch circuit | AFS OFF SWITCH CIRCUIT |
| BEAN communication malfunction | - | |
| Combination meter assembly | - | |
| AFS ECU | AFS PROBLEM SYMPTOMS |
HINT:
- *1: When the AFS indicator light does not come on or blink despite the symptom being indicated, check the battery voltage.
- *2: Check if the headlight swivel motor turns smoothly by hand. If the motor does not turn, replace it with a new one. If the motor still does not turn, replace the headlight assembly with a new one.
- *3: Before the procedure, check that the AFS OFF switch is not pushed.