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Home › Toyota › 2009 › Yaris Base, 4D Hatchback › Repair and Diagnosis › External Pages › Different car › Section 16 (Lighting System) › Lighting System › System Description

System Description

WARNING: This page is about a different car, the 2009 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
  1. PARTS DESCRIPTION 
    PARTS DESCRIPTION

    Components Function
    Automatic light control sensor Detects ambient light and sends information to main body ECU
    Hazard warning switch On or off state is sent to flasher relay
    Stop light switch Sends brake pedal state to rear combination light and high mount stop light
    H-LP relay Turns headlight on when it is actuated by headlight ON demand signal via main body ECU
    T-LP relay Turns taillight and illumination on when it is actuated by taillight ON demand signal via main body ECU
    DIM relay Turns headlight (high beam) on when it is actuated by headlight ON demand signal via main body ECU
    DRL relay Controls headlight (low beam) when it is actuated by DRL ON demand signal via main body ECU
    Daytime running light relay Controls headlight (low beam) when it is actuated by DRL ON demand signal via main body ECU
    Door courtesy switch Detects door open / close state and sends information to respective main body ECU
    Door unlock detection switch Detects door lock / unlock state and sends information to respective main body ECU
    Headlight beam level control actuator Moves headlight (low beam) up and down according to the information from headlight beam level control ECU
    Height control sensor Detects vehicle height and sends corresponding information to headlight beam level control ECU
    Combination meter Sends headlight level warning according to information from headlight beam level control ECU
  2. OPERATION DESCRIPTION 
    1. Manual lighting system
      1. The main body ECU receives the following:
        • Light switch tail signal
        • Light switch head signal
        • Light switch high beam signal
        • Front fog switch signal
        • Lighting system passing signal
      2. The main body ECU controls the following based on the signals listed in (1).
        • H-LP relay ON signal Sent when light switch head signal is received.
        • T-LP relay ON signal Sent when light switch tail signal and light switch head signal are received.
        • DIM relay ON signal Sent when light switch high beam signal is received.
        • FR FOG relay ON signal Sent when light switch tail and front fog switch signals are received.
      3. The main body ECU controls the on / off operation of the following based on the signals listed in (2):
        • Headlight (low)
        • Headlight (high)
        • Clearance light
        • Side marker light
        • Front fog light
        • Taillight
        • License plate light
        • Room lights
    2. Automatic lighting system
      1. The main body ECU receives the following:
        • Light switch auto signal
        • Light control switch signal
      2. The main body ECU controls the following based on the signals listed in (1):
        • H-LP relay ON signal Sent according to the illuminance information from the light control signal when the light switch auto signal is received.
        • T-LP relay ON signal Sent according to the illuminance information from the light control signal when the light switch auto signal is received.
      3. The main body ECU controls the on / off operation of the following based on the signals listed in (2).
        • Headlight (low)
        • Clearance light
        • Side marker light
        • Taillight
        • License plate light
    3. Daytime running light system
      1. The main body ECU receives the following:
        • Light switch tail signal
        • Light switch head signal
        • Light switch auto signal
        • Light control signal
        • Ready condition signal
        • Parking brake switch signal
      2. The main body ECU controls the following based on the signals listed in (1).
        • H-LP relay ON signal

          Sent when the ready condition signal has been received but the light switch head and parking brake switch signals have not been received.

          Sent when the ready condition signal has been received but the parking brake switch signal and the illuminance information from the light control have not been received while receiving the light switch auto signal.

        • DIM relay ON signal

          Sent when the relay condition signal has been received but the light switch head and parking brake switch signals have not been received.

          Sent when the ready condition signal has been received but the parking brake switch signal and the illuminance information from the light control have not been received while receiving the light switch auto signal.

        • DRL NO. 4 relay ON signal

          Sent when the ready condition signal has been received but the light switch head and parking brake switch signals have not been received.

          Sent when the ready condition signal has been received but the parking brake switch signal and the illuminance information from the light control have not been received while receiving the light switch auto signal.

        • PWM output signal

          Sent when the ready condition signal has been received but the light switch tail, light switch head, and parking brake switch signals have not been received.

          Sent when the ready condition signal has been received but the parking brake switch signal and the illuminance information from the light control have not been received while receiving the light switch auto signal.

      3. The main body ECU controls the following based on the signals listed in (2):
        • Headlight (Low)
    4. Light auto turn off system
      1. The main body ECU receives the following:
        • Light switch tail signal
        • Light switch head signal
        • Light switch auto signal
        • Front fog switch signal
        • Power switch signal
        • Light control signal
        • Driver's seat courtesy switch signal
      2. The main body ECU controls the following based on the signals listed in (1).
        • H-LP relay ON signal

          Terminates communication when the power switch ON (IG) signal terminates and the driver's seat courtesy switch signal is received while sending the H-LP relay ON signal. The H-LP relay ON signal results from receiving the light switch head signal and illuminance information from the light control signal.

        • T-LP relay ON signal

          Terminates communication when the power switch ON (IG) signal terminates and the driver's seat courtesy switch signal is received while sending the T-LP relay ON signal. The T-LP relay ON signal results from receiving the light switch head signal and illuminance information from the light control signal.

      3. The main body ECU controls the on / off operation of the following based on the signals listed in (2).
        • Headlight (low)
        • Headlight (high)
        • Clearance light
        • Side marker light
        • Front fog light
        • Taillight
        • License plate light
    5. Illuminated entry system
      1. The main body ECU receives the following:
        • Driver side door courtesy switch signal
        • Front passenger side door courtesy switch signal
        • Rear LH side door courtesy switch signal
        • Rear RH side seat door courtesy switch signal
        • Driver side door lock signal
        • Passenger side door lock signal (w/ Smart key system, w/ Theft deterrent system)
        • Power switch signal
      2. The main body ECU controls the following based on the signals listed in (1):
        • Illumination ON demand signal Sent when the respective door courtesy switch signals are received.

          Sent when the respective door lock signals are received.

          Sent when the power switch ON (IG) and power switch ON (ACC) signals are not received.

      3. The main body ECU controls on / off and fade-in / fade-out operations of the following based on the signals listed in (2):
        • Key slot light
        • No. 1 room light
        • Personal light (Overhead junction block)
    6. Auto headlight leveling system
      1. The headlight beam level control ECU receives the following:
        • H-LP relay ON signal
        • Vehicle height sensor signal
        • Vehicle speed signal
      2. The headlight beam level control ECU controls the following based on the signals listed in (1).
        • Leveling motor operation demand signal. Sent based on the vehicle height sensor signal and vehicle speed sensor when the HLP relay ON signal is received.

          The headlight beam level control ECU receives vehicle speed signal and determines the driving condition according to the table below, and then starts / terminates controlling on the headlight leveling actuator.

          HEADLIGHT BEAM LEVEL CONTROL ECU CONTROLS

          Vehicle Speed Mode Control
          Less than 0.7 km/h (0.4 mph) While stopping Controls
          More than 30 km/h (19 mph) or less than 180 km/h (112 mph) While driving at constant speed Controls
          More than 30 km/h (19 mph) or less than 180 km/h (112 mph) While accelerating Does not control
          More than 180 km/h (112 mph) While driving at high speed Does not control
          More than 0.7 km/h (0.4 mph) or less than 30 km/h (19 mph) While driving at low speed Does not control
      3. The headlight beam level control ECU controls the following based on the signal listed in (2).
        • Headlight beam leveling actuator
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