System Description

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

PARTS DESCRIPTION

Components	Function
Automatic light control sensor	Detects ambient light and sends the information to the body ECU.
HEAD relay	Turn the headlight on when it is actuated by the headlight ON demand signal by the front controller.
TAIL relay	Turns the tail light and illumination on when it is actuated by the tail light ON demand signal via the body ECU
Door courtesy switch	Detects the door open / close state and sends the respective information to the body ECU.
Door unlock detection switch	Detects the door lock / unlock state and sends the respective information to the body ECU.
Alternator	Detects the engine start / stop state and sends the information to the headlight beam level control ECU.
Skid control ECU	Detects the vehicle speed and sends the information to the headlight beam level control ECU.
Height control sensor	Detects the vehicle height and sends the corresponding information to the headlight beam level control ECU.
Combination meter	Sends headlight beam level warning according to the information from the headlight beam level control ECU.
Headlight beam level control motor	moves the headlight (low beam) up and down according to the information from the headlight beam level control ECU.

OPERATION DESCRIPTION
1. Illumination control system (Illuminated entry system):
  1. The body ECU receives the following (A):
    - Door courtesy switch signal
    - Door detection switch signal
    - Ignition switch signal
  2. The body ECU controls the following based on the signals listed in "A":
    - Illumination operation signal
  3. The body ECU controls on / off and fade-in / fade-out operation of the following:
    - Front interior light
    - Ignition key cylinder light or engine switch illumination
2. Manual light control system:
  This system functions if lights such as the headlights and tail lights come on by manual operation of the light control switch.
  1. The body ECU receives the following (B):
    - Light control switch signal
    - Headlight dimmer switch signal
    - Fog light switch signal
  2. The body ECU controls the following based on the signals listed in "B":
    - Headlight ON signal
    - Tail light ON signal
    - High beam ON signal
    - Front fog light ON signal
3. Light auto turn off system:
  When the headlights and tail lights are on through the operation of the automatic light control switch, if the ignition switch is turned off and all doors are closed, this system continues to illuminate the headlights and tail lights for approximately 30 seconds, and then turns off the headlights. However, with all the doors locked manually, using the door lock button, using the key, or pressing "LOCK" on the wireless remote will turn the headlights and tail lights of immediately.
  1. The body ECU receives the following (C):
    - Door courtesy switch signal
    - Ignition switch on (IG) signal
  2. The multiplex network body ECU controls the following based on the signals listed in "C" (D):
    - Tail light ON signal
    - Headlight ON signal
    - High beam ON signal
    - Fog light signal
  3. The body ECU controls the illuminating period of the following based on the signals listed in "D":
    - Fog light
    - Tail light
  4. The front controller receives headlight ON and the high beam ON signals from the body ECU, and then controls the illuminating period of the following based on the signal listed in "D":
    - Headlight (Low)
    - Headlight (Hi)
4. Automatic light control system:
  When the light control switch is in the AUTO position, the automatic light control sensor detects ambient light and automatically turns the headlights and tail light on or off accordingly.
  1. The body ECU receives the following (E):
    - Light control switch signal
    - Automatic light control sensor signal
  2. The body ECU controls the following based on the signals listed in "E":
    - Headlight ON signal
    - Tail light ON signal
  3. The body ECU controls on / off operation of the following:
    - Tail light
  4. The front controller receives the headlight ON signal from the body ECU, and then controls on / off operation of the following:
    - Headlight
5. Daytime running light system:
  This system is directly connected to the high-beam headlights and is designed to automatically activate the daytime running lights in order to remain highly visible to other vehicles.
  1. The body ECU receives the following (F):
    - Ignition switch signal
    - Generator signal
    - Parking brake switch signal
    - Light control switch signal
  2. The body ECU controls the following based on the signals listed in "F":
    - DRL relay operation signal
  3. The front controller receives the high beam ON signal from the body ECU, and then controls on / off operation of the following:
    - Headlight (Hi)
6. Turn signal light system
  1. The body ECU receives the following (G):
    - Right turn signal
    - Left turn signal
  2. The body ECU controls the following based on the signals listed in "G" (H):
    - Right turn ON signal
      Sent when the right turn signal or hazard warning signal is received.
    - Left turn ON signal
      Sent when the left turn signal or hazard warning signal is received.
  3. The body ECU controls on / off operation of the following based on the signals listed in "H":
    - Right turn signal light
    - Left turn signal light
7. Headlight beam level control system
  1. The headlight beam level control ECU receives the following (I):
    - HEAD relay ON signal
    - Vehicle height sensor signal
    - Vehicle speed signal
    - Alternator signal
  2. The headlight beam level control ECU controls the following based on the signals listed in "I" at engine start (J):
    - Level control motor operation demand signal:
      Sent based on the vehicle height sensor signal and vehicle speed sensor when the HEAD relay ON signal is received.
    - Headlight beam level control warning indicator light signal:
      Sent to the combination meter when the headlight beam level control ECU is malfunctioning.
  3. The headlight beam level control ECU control the following based on the signals listed in "J".
    - Headlight beam level control motor
    - Headlight beam level control warning indicator light