System Description

WARNING: This page is about a different car, the 2004 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

SYSTEM DESCRIPTION
1. Description
  The LEXUS link system has been adopted primarily for the purpose of saving human lives in case of an accident and as a preventive measure against theft. This system contains the following 8 functions: automatic emergency call, manual emergency call, service call, memo record, door lock/unlock, theft notification, self diagnosis, and voice message. To activate these functions, press the button for the function you would like to activate. Communication with the LEXUS link center is performed with the telephone transceiver assy and telephone antenna provided on the vehicle roof. If an accident happens and a connection with the LEXUS link center is made, the operator at the center specifies the vehicle position with GPS data from the GPS antenna located on the upper back panel, which is on the right side of the luggage room.
2. System function
  
  Fig 1: System Function Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Function of main components
  
  Fig 2: Function Of Main Components Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. System operation
  1. LED Indicator
    - When the ignition switch is turned ON, the telephone ECU assy (Mayday ECU) illuminates LED A and B on the telephone switch assy. LED A is amber for a few seconds and then its color changes to green. LED B is red a for few seconds and then turns off.
    - When the ignition switch turns ON and 10 seconds have passed, the telephone ECU assy determines the operating condition of the LEXUS link system. Depending on whether or not a system malfunction is present, the ECU causes the indicator lights to illuminate or start blinking.
    - Descriptions of the meaning of the illumination or blinking of the indicator lights are below.
    Fig 3: System Table
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Automatic Emergency Call
  - In the event of an accident in which the airbags are deployed, the telephone ECU assy (Mayday ECU) receives an airbag deployment signal from the airbag sensor assy center. Then the telephone ECU assy automatically makes an emergency call to the LEXUS link center and plays a recording indicating that an emergency call is being made. If the telephone ECU assy stops receiving signals from the airbag sensor assy center, the telephone ECU assy assumes that an open circuit in the wire harness has been caused by a collision and makes an emergency call.
  - When the ignition switch is ON and power is no longer supplied by the battery of the vehicle, the telephone ECU assy determines that an open circuit in the wiring harness has been caused by a collision and makes an emergency call using the portable phone-L battery.
  Fig 4: Automatic Emergency Call Circuit Flow Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Manual Emergency Call
  In the event of an accident in which the airbags are not deployed, or in case of an emergency, the EMERGENCY button provided on the roof console box can be manually operated to place an emergency call to the LEXUS link center. Then the telephone ECU assy plays a recording indicating that an emergency call is being made.
  
  Fig 5: Manual Emergency Call Circuit Flow Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Service Call
  - By pressing the SERVICE button on the roof console box's telephone switch assy (Mayday switch), the telephone ECU assy (Mayday ECU) makes a service call to the LEXUS line center, and plays a recording indicating that a service call is being made.
  - If part of the system is removed (for example, for maintenance service) or if signal output from the airbag sensor assy center to the telephone ECU assy stops after the ignition switch is turned ON, the telephone ECU assy determines that a malfunction has occurred in the circuit and makes a service call.
  Fig 6: Service Call Circuit Flow Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Memo Record
  - By pressing the REC button on the roof console box's telephone switch assy (MAYDAY switch) while a call is being made to the LEXUS link center, the conversation can be recorded into the telephone ECU assy. Pressing the REC button when no call is being made can also record audio (for example, your voice).
  - By pressing the PLAY button on the roof console box's telephone switch assy (Mayday switch), any audio (for example, a conversation or your voice) previously recorded into the telephone ECU assy can be played back.
    
    Fig 7: Memo Record Circuit Flow Chart
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  - Door Lock/Unlock
    If the driver is locked out of the vehicle with the key in the ignition or somewhere in the vehicle, the LEXUS link center can remotely unlock the vehicle doors. The driver only needs to contact the LEXUS link center and provide his vehicle ID code.
    
    Fig 8: Door Lock/Unlock Circuit Flow Chart
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  - Theft Notification
    If the vehicle is stolen, the theft deterrent ECU will send a warning signal to the telephone ECU assy (Mayday ECU), which will then make an emergency call to the LEXUS link center to notify of the vehicle theft. The roof console box's microphone will then turn ON automatically and be able to monitor and record any voices in the vehicle.
    
    Fig 9: Theft Notification Circuit Flow Chart
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002