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Problem Symptoms Table

WARNING: This page is about a different car, the 2006 Lexus RX 400h. However, it is still accessible from the selected car via links, so may be relevant.
  1. HEADLIGHT AND TAILLIGHT SYSTEM 
    HEADLIGHT AND TAILLIGHT SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    "Low beam" does not comes on (One side). 1. MAIN fuse, H-LP L LWR fuse, H-LP R LWR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. HEADLIGHT RELAY CIRCUIT 
    5. Instrument panel junction block assembly
    "Low beam" does not comes on (Both side). 1. MAIN fuse, H-LP L LWR fuse, H-LP R LWR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. HEADLIGHT RELAY CIRCUIT 
    5. Instrument panel junction block assembly
    "High beam" does not comes on (One side). 1. MAIN fuse, H-LP L UPR fuse, H-LP R UPR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. Dimmer relay circuit
    5. Instrument panel junction block assembly
    "High beam" does not comes on (Both side). 1. MAIN fuse, H-LP L UPR fuse, H-LP R UPR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. Dimmer relay circuit
    5. Instrument panel junction block assembly
    "Low beam" and "High beam" does not come on (One side). 1. MAIN fuse, DRL fuse, H-LP L UPR fuse, H-LP R UPR fuse, H-LP L LWR fuse, H-LP R LWR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. HEADLIGHT RELAY CIRCUIT 
    5. Dimmer relay circuit
    6. Instrument panel junction block assembly
    "Low beam" and "High beam" does not come on (Both side). 1. MAIN fuse, DRL fuse, H-LP L UPR fuse, H-LP R UPR fuse, H-LP L LWR fuse, H-LP R LWR fuse
    2. Bulb
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. HEADLIGHT RELAY CIRCUIT 
    5. Dimmer relay circuit
    6. Instrument panel junction block assembly
    "Flash" does not come on. (Low beam and Hi-Beam is normal) 1. LIGHT CONTROL SWITCH CIRCUIT 
    2. Instrument panel junction block assembly
    Headlight is dark. 1. Bulb
    2. Wire harness or connector
    Taillight does not come on (All). 1. TAIL fuse
    2. LIGHT CONTROL SWITCH CIRCUIT 
    3. TAIL relay circuit
    4. IGNITION SWITCH CIRCUIT 
    5. DOOR COURTESY SWITCH CIRCUIT 
    6. Instrument panel junction block assembly
    Only one taillight comes on. 1. Bulb
    2. Wire harness or connector
    Rear combination light does not come on. 1. Rear combination light assembly
    2. Wire harness or connector
    Daytime running light system does not operate. 1. LIGHT CONTROL SWITCH CIRCUIT 
    2. Generator signal circuit
    3. PARKING BRAKE SWITCH CIRCUIT 
    4. IGNITION SWITCH CIRCUIT 
    5. Dimmer relay circuit
    6. Instrument panel junction block assembly
  2. AUTOMATIC LIGHT CONTROL SYSTEM 
    AUTOMATIC LIGHT CONTROL SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Automatic light control system does not operate. 1. LIGHT CONTROL SWITCH CIRCUIT 
    2. IGNITION SWITCH CIRCUIT 
    3. AUTOMATIC LIGHT CONTROL SENSOR CIRCUIT 
    4. Instrument panel junction block assembly
  3. LIGHT AUTO TURN OFF SYSTEM 
    LIGHT AUTO TURN OFF SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Light auto turn off system does not operate. 1. LIGHT CONTROL SWITCH CIRCUIT 
    2. IGNITION SWITCH CIRCUIT 
    3. DOOR COURTESY SWITCH CIRCUIT 
    4. Instrument panel junction block assembly
  4. FOG LIGHT SYSTEM 
    FOG LIGHT SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Front fog light does not come on with light control switch in TAIL or HEAD position. 1. FOG fuse
    2. FOG, TAIL relay
    3. LIGHT CONTROL SWITCH CIRCUIT 
    4. FRONT FOG LIGHT CIRCUIT 
    5. Instrument panel junction block assembly
    Only one front fog light does not come on. 1. Bulb
    2. Wire harness or connector
  5. TURN SIGNAL AND HAZARD WARNING SYSTEM 
    TURN SIGNAL AND HAZARD WARNING SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    "Hazard" and "Turn" do not come on. 1. HAZ fuse
    2. GAUGE fuse
    3. IG1 relay
    4. Ignition switch
    5. TURN SIGNAL FLASHER RELAY 
    6. Wire harness or connector
    Hazard warning light does not come on (Turn is normal). 1. HAZARD WARNING SWITCH 
    2. Wire harness or connector
    Turn signal does not come on (Hazard is normal). 1. Headlight dimmer switch (turn signal switch). See HEADLIGHT DIMMER SWITCH 
    2. Wire harness or connector
    Turn signal does not come on in one direction. 1. Headlight dimmer switch (turn signal switch). See HEADLIGHT DIMMER SWITCH 
    2. Wire harness or connector
    Only one bulb does not come on. 1. Bulb
    2. Wire harness or connector
  6. STOP LIGHT SYSTEM 
    STOP LIGHT SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Stop light does not operate (All). 1. STOP fuse
    2. BRK relay
    3. STOP LIGHT SWITCH 
    4. Rear Junction Block
    5. Wire harness or connector
    Only one stop light does not operate. 1. Rear Junction Block
    2. Rear combination light assembly
    3. Wire harness or connector
  7. ILLUMINATED ENTRY SYSTEM 
    ILLUMINATED ENTRY SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Illuminated entry of Multiplex network body ECU control does not operate (All). 1. IGNITION SWITCH CIRCUIT 
    2. DOOR LOCK POSITION CIRCUIT 
    3. DOOR COURTESY SWITCH CIRCUIT 
    4. ILLUMINATION CIRCUIT 
    5. Instrument panel junction block assembly
  8. OVERHEAD CONSOLE ILLUMINATION SYSTEM 
    OVERHEAD CONSOLE ILLUMINATION SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Overhead console illumination of multiplex network body ECU control does not operate. 1. Overhead ECU
    2. IGNITION SWITCH CIRCUIT 
    3. Overhead console illumination circuit. See STEP ILLUMINATION CIRCUIT 
    4. Instrument panel junction block assembly
  9. STEP LIGHT SYSTEM 
    STEP LIGHT SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Step light of body ECU control does not operate. 1. IGNITION SWITCH CIRCUIT 
    2. Park/neutral position switch. See WIRING DIAGRAM
    3. DOOR LOCK POSITION CIRCUIT 
    4. DOOR COURTESY SWITCH CIRCUIT 
    5. STEP ILLUMINATION CIRCUIT 
    6. Instrument panel junction block assembly
  10. INSIDE HANDLE ILLUMINATION LIGHT SYSTEM 
    INSIDE HANDLE ILLUMINATION LIGHT SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Inside handle illumination light of body ECU control does not operate. 1. IGNITION SWITCH CIRCUIT 
    2. Park/neutral position switch. See WIRING DIAGRAM
    3. DOOR LOCK POSITION CIRCUIT 
    4. DOOR COURTESY SWITCH CIRCUIT 
    5. INSIDE HANDLE ILLUMINATION LIGHT CIRCUIT 
    6. Instrument panel junction block assembly
  11. HEADLIGHT BEAM LEVEL CONTROL SYSTEM 
    HEADLIGHT BEAM LEVEL CONTROL SYSTEM PROBLEM SYMPTOMS

    Symptom Suspected area
    Headlight beam level control system does not operate. 1. HEADLIGHT BEAM LEVEL CONTROL ACTUATOR CIRCUIT 
    2. HEIGHT CONTROL SENSOR CIRCUIT 
    3. HEADLIGHT BEAM LEVEL CONTROL ECU COMMUNICATION CIRCUIT 
    4. HEADLIGHT BEAM LEVEL CONTROL ECU POWER SOURCE CIRCUIT 
    5. Headlight beam level control ECU
    Headlight beam warning light comes on (Headlight beam level control is normal). 1. Combination meter assembly
    2. Wire harness or connector
    3. Headlight beam level control ECU
    Headlight beam warning light does not come on (Headlight beam level control is normal). 1. GAUGE fuse
    2. Combination meter assembly
    3. Wire harness or connector
    4. Headlight beam level control ECU
  12. AFS 
    AFS PROBLEM SYMPTOMS

    Symptom Suspected area
    AFS does not operate. (Does not initialize) 1. AFS ECU POWER SOURCE CIRCUIT 
    2. AFS ECU
    Does not initialize. (AFS is normal) 1. DTC B2419 BEAN COMMUNICATION MALFUNCTION 
    2. DTC B2415 VEHICLE SPEED SENSOR MALFUNCTION 
    3. AFS ECU
    Only one swivel motor is not initialized. 1. Headlight assembly or swivel motor stuck
    2. HEADLIGHT SWIVEL ECU COMMUNICATION MALFUNCTION 
    3. HEADLIGHT SWIVEL MOTOR MALFUNCTION 
    4. AFS ECU
    Each side swivel motor is not initialized. 1. AFS ECU POWER SOURCE CIRCUIT 
    2. HEADLIGHT SWIVEL ECU COMMUNICATION MALFUNCTION 
    3. AFS ECU
    Headlight leveling motor is not initialized. 1. HEADLIGHT BEAM LEVEL CONTROL MOTOR MALFUNCTION 
    2. AFS ECU
    Only swivel control does not operate or malfunction. 1. Steering sensor calibration malfunction (Go to  2)
    2. STEERING POSITION SENSOR MALFUNCTION 
    3. DTC B2415 VEHICLE SPEED SENSOR MALFUNCTION 
    4. DTC B2419 BEAN COMMUNICATION MALFUNCTION 
    5. HEADLIGHT SWIVEL ECU COMMUNICATION MALFUNCTION 
    6. HEADLIGHT SWIVEL MOTOR MALFUNCTION 
    7. AFS ECU
    Swivel control and leveling control does not operate. 1. HEIGHT CONTROL SENSOR MALFUNCTION 
    2. AFS ECU
    AFS OFF indicator light does not come on. 1. Bulb
    2. Combination meter assembly
    3. AFS OFF SWITCH CIRCUIT 
    4. AFS ECU
  13. OTHERS 
    OTHERS PROBLEM SYMPTOMS

    Symptom Suspected area
    Vanity light does not operate. 1. Bulb
    2. Wire harness or connector
    Back up light does not come on (All). 1. Bulb
    2. Park/neutral position switch. See WIRING DIAGRAM
    3. BACK-UP LIGHT CIRCUIT 
    4. HV control ECU
    Rear interior light, back door courtesy light and luggage light does not come on (All). 1. Bulb
    2. TAIL fuse
    3. TAIL relay
    4. Wire harness or connector
    5. Instrument panel junction block assembly
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