Global Positioning System: Description and Operation
System Diagram:
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
a. 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.
b. System function
c. Function of main components
d. System operation
1. LED Indication
- 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 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 LEDs to illuminate or start blinking.
- Descriptions of the meaning of the illumination or blinking of the LEDs.
2. 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.
3. 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.
4. 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 link 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.
5. 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.
6. 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.
7. Theft Notification
If the vehicle is stolen, the theft warning 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.
SYSTEM OUTLINE
1. AUTOMATIC EMERGENCY CALL
In case of an accident where the airbag deployed, the system automatically makes an emergency call to the call center. Even if the driver is unable to push the call button, the system will do so automatically if the airbag deploys.
In this case, the vehicle position is reported to the call center through the GPS and the correct place of the accident can be located.
2. MANUAL EMERGENCY CALL
In case of an accident where the airbag did not deploy, the driver can make an emergency call by operating the call button.
3. SERVICE CALL
The driver can obtain various information such as road guidance from the call center by operating the service button
4. MEMORANDUM RECORD
The conversation between the call center and the driver can be recorded and played back.
5. DOOR LOCK/UNLOCK
The doors can be locked/unlocked by remote control from the call center.
6. THEFT DETECTION
In case of car theft, the call center is reported of the theft automatically, as well as the current vehicle position.
Cases where the system will not make a call:
- The system components or wire harnesses are damaged due to the accident.
- The vehicle is out of the communication area.
- The call center has stopped its service.
- The vehicle has turned over and the antenna is shut off.
- The GPS can not be received, and the correct position can not be located.