System Description

The system representations shown below are intended to show concept of operation, and may not precisely reflect the construction of the system on the vehicle.

AUTOMATIC LIGHT CONTROL SYSTEM
1. General
  1. When the light control switch is in the AUTO position, the automatic light control system detects ambient light levels and controls the headlights, parking lights, taillights, marker lights, and license plate lights.
    - The main body ECU RH controls this system.
    - The headlight dimmer switch includes the tilt and telescopic switch, fog switch, turn switch, dimmer switch, and light control switch. The headlight dimmer switch signals are received by the windshield wiper switch assembly, and the windshield wiper switch assembly forwards these signals to the main body ECU RH using the Body Electronics Area Network (BEAN).
    - A direct headlight backup link (HEAD) exists between the windshield wiper switch assembly and the main body ECU RH. If this link is grounded, the headlights will illuminate.
    - Ambient light levels are detected by the light control sensor that is integrated in the air conditioning system's solar sensor. This signal is received directly by the main body ECU RH (cowl side junction block RH).
    - The dimmer circuit in the combination meter controls the ground for the panel illumination.
    - The combination meter bases the control of the panel illumination on signals received from the light control rheostat, and other inputs.
    - The main body ECU RH controls the taillights and panel illumination using the tail relay that is built into the main body ECU LH (cowl side junction block LH).
    - The main body ECU RH controls the low beam illumination using the HEAD LP relay.
      
      Fig 1: Identifying Front Controller
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    - The front controller operates the high beams using the IC relays (*1) or HEAD HI relay (*2) built into the front controller (engine room No. 2 relay block).
    - The front controller operates the front marker lights using the FR TAIL relay that is built into the front controller (engine room No. 2 relay block).
    - The front controller operates the front parking lights using the IC relay (*3) or FR TAIL relay (*4) that is built into the front controller (engine room No. 2 relay block).
    - The front controller operates the front fog lights using the FR FOG relay that is built into the front controller (engine room No. 2 relay block).
    - *1: Except HID Type
    - *2: for HID Type
    - *3: HID Type, w/ Daytime Running Light
    - *4: Except *3
MANUAL LIGHT CONTROL SYSTEM
1. The function of the system is similar to the automatic light control system, except the system is controlled according to the driver's inputs.
BI-FUNCTION
1. The models with HID (High Intensity Discharge) headlights have a Bi-function. This Bi-function increases the upper illumination area of the discharge bulb (low/high beam) when the high beam is turned on.
  - If the low beam is selected, the upper illumination area of the discharge bulb is blocked by a shade and only the lower illumination area is used. If the high beam is selected, the headlight solenoid slides the shutter (shade) down to allow use of the upper illumination area, thus increasing the illumination area and improving visibility when the high beam is on.
  - This function is activated by the front controller. The front controller receives a high beam turn ON signal from the main body ECU RH and activates the headlight solenoid built into the headlight unit to slide the shade down.
  Fig 2: Identifying Headlight Solenoid Circuit Description
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HID HEADLIGHT SYSTEM
1. This system consists primarily of the light control switch, windshield wiper SW assembly, main body ECU RH, HEAD LP relay, discharge bulbs, and light control ECUs.
  - The main body ECU RH controls the low beam illumination using the HEAD LP relay.
  - The BEAN network is used for communication.
  - A HEAD backup link exists between the windshield wiper switch and the main body ECU RH.
  - The light control ECUs transform the voltage that is input from the battery to a high voltage of up to 22, 000 V and apply this voltage to the discharge bulbs in order to illuminate them.
  - A fail-safe function is provided as a countermeasure against the high voltage that is generated in case that a problem occurs in the headlight system.
  Fig 3: HID Headlight System Lighting Diagram
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  NOTE:
  For safety reasons, do not attempt to measure the voltage output from a light control ECU.
AUTOMATIC HEADLIGHT BEAM LEVEL CONTROL SYSTEM
1. When the headlights are on, the automatic headlight beam level control system operates the headlight level actuators in accordance with the movement of the vehicle.
  - The automatic headlight beam level control system mainly consists of the headlight leveling ECU assembly, front height control sensor, rear height control sensor, and two headlight level actuators. The headlight leveling ECU assembly controls the system.
  - The ECU detects the movement of the suspension from the front and rear height control sensors, and the vehicle speed from the front RH and LH speed sensors.
  - The ECU then controls the headlight level actuator based on this information, in order to change the headlight reflector angle.
2. Initial Set Control
  - The headlight leveling ECU assembly executes the initial setting of the stepper motors at engine-start.
3. Fail-Safe Function
  - If the headlight leveling ECU assembly detects a malfunction in the automatic headlight beam level control system, the headlight leveling ECU assembly effects fail-safe control. At the same time, the headlight leveling ECU assembly indicates the system warning the multi-information display in order to inform the driver of the problem.
DAYTIME RUNNING LIGHT SYSTEM (Except HID Type)
1. The daytime running light system is designed to automatically illuminate the headlights (dimmed high beams), during the daytime to make the car more visible to other vehicles.
  - The main body ECU RH and front controller control this system. The main body ECU RH transmits a turn ON signal to the front controller, and the front controller illuminates the high beams using duty control.
  - This system is enabled when the conditions below are met:
    - Engine switch is on (IG)
    - Engine speed signal is input (engine running condition)
    - Light control switch is in off, tail, or AUTO position (if headlight-on control is not being performed by the automatic light control)
    - Parking brake switch is off
DAYTIME RUNNING LIGHT SYSTEM (for HID Type)
1. The daytime running light system is designed to automatically illuminate the headlights (high-intensity parking lights), during the daytime to make the car more visible to other vehicles.
  - There are 2 LED type parking light circuits in each headlight. One is for a conventional low-intensity parking light that illuminates with the taillights, and the other is for the high-intensity parking light that is used for the DRL system. These circuits are operated via independent IC relays in the front controller.
  - The main body ECU RH and front controller control this system. The main body ECU RH transmits a turn ON signal to the front controller, and the front controller illuminates the high-intensity parking lights.
  - This system is enabled when the conditions below are met:
    - Engine switch is on (IG)
    - Engine speed signal is input (engine running condition)
    - Light control switch is in off, tail, or AUTO position (if headlight-on control is not being performed by the automatic light control)
    - Parking brake switch is off

ILLUMINATED ENTRY SYSTEM

General

The illuminated entry system has the seven control functions shown in the following chart:

Control	Operation	Outline	Lights that Operate
Actuation Area-linked	Turn ON	When the key enters any actuation area around the doors, the front and rear seat illumination turns on.	Front Seat Illumination Rear Seat Illumination Door Mirror Foot Lights Scuff Plate Lights
Transmitter-linked	Turn ON	When the following condition is satisfied, the lights that operate turn on. Any door is unlocked using the transmitter.	Front Seat Illumination Rear Seat Illumination Footwell Lights*3 Door Mirror Foot Lights Scuff Plate Lights
Door Open-linked	Turn ON	When the following condition is satisfied, the lights that operate turn on. Any door is opened.	Engine Switch Illumination Front Interior Lights Rear Interior Light Scuff Plate Lights Door Courtesy Lights Footwell Lights*3
Door Close-linked	Turn OFF*1	When the following condition is satisfied, the lights that operate turn off. All doors are closed.	Front Seat Illumination Rear Seat Illumination Engine Switch Illumination Front Interior Lights Rear Interior Light Scuff Plate Lights Door Courtesy Lights Footwell Lights*3 Door Mirror Foot Lights
Door Lock-linked	Turn OFF*2	When the following condition is satisfied, the lights that operate turn off. All doors are locked.
Power Source-linked	Turn ON	When the following condition is satisfied, the shift illumination turns on. Power source is changed from OFF to ACC or IG-ON.	Shift Illumination
	Turn ON	When the following condition is satisfied, the footwell lights turns on. Power source is changed from OFF to IG-ON.	Footwell Lights*3
	Turn OFF*2	When the following condition is satisfied, the lights that operate turn off. Power source is changed from OFF to ACC or IG-ON.	Front Seat Illumination Rear Seat Illumination Engine Switch Illumination Scuff Plate Lights
Shift Position-linked^*5	Turn OFF	When the following conditions are satisfied, the lights that operate turn off. IG-ON. Shift lever is in a position other than P.	Door Mirror Foot Lights
Parking Brake Switch-linked^*6	Turn OFF	When the following conditions are satisfied, the lights that operate turn off. IG-ON. Parking Brake Switch off	Door Mirror Foot Lights
Battery Saving	Turn OFF	When the following conditions are satisfied, the lights that operate turn off. A key is not in the actuation area. There are no changes in the condition of the doors for 20 minutes.	Front Seat Illumination^4 Rear Seat Illumination^4 Engine Switch Illumination Front Interior Lights Rear Interior Light Scuff Plate Lights Footwell Lights*3

*1: Illuminates for approximately 15 seconds, and then fades out (fades out over three seconds).
*2: Stops the illumination and starts to fade out immediately (fades out over three seconds).
*3: The footwell lights go off when the light control rheostat is adjusted to the minimum level.
*4: If the communication between the main body ECU RH and LH is interrupted, the main body ECU LH turns off the illumination after 25 minutes have elapsed.
*5: for A/T
*6: for M/T

TURN SIGNALS
1. The turn signals are front, rear and side lights that can be used to indicate a change of vehicle direction.
  - The turn signal switch signals are received by the windshield wiper switch assembly (combination switch ECU).
  - The main body ECU LH operates the turn signal flasher.
  - The turn signal flasher operates the signal lights.
HEADLIGHT CLEANER SYSTEM
1. Some vehicles are provided with a headlight cleaner system. More details on the headlight cleaner system operation can be found in the wiper section.