System Description

1. If the symptom is applicable to any of the following, it is intended behavior, and not a malfunction.
   SYMPTOM ANSWER
   
   

   Symptom	Answer
   A longer route than expected is chosen.	Depending on the road conditions, the navigation ECU may determine that a longer route is quicker.
   Even when distance priority is high, the shortest route is not shown.	Some paths may not be advised due to safety concerns.
   When the vehicle is put into motion immediately after the engine starts, the navigation system deviates from the actual position.	If the vehicle starts before the navigation system activates, the system may not react.
   When running on certain types of roads, especially new roads, the vehicle position deviates from the actual position.	When the vehicle is driving on new roads not available on the map disc, the system attempts to match it to another nearby road, causing the position mark to deviate.

2. The following symptoms are not a malfunction, but are caused by errors inherent in the GPS, gyro sensor, speed sensor, and navigation ECU.
   1. The current position mark may be displayed on a nearby parallel road.
      Fig 1: Identifying Current Position Mark Displayed On Nearby Parallel Road

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Immediately after a fork in the road, the current vehicle position mark may be displayed on the wrong road.
      Fig 2: Identifying Current Vehicle Position Mark Displayed On Wrong Road

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. When the vehicle turns right or left at an intersection, the current vehicle position mark may be displayed on a nearby parallel road.
      Fig 3: Identifying Current Vehicle Position Mark Displayed On Nearby Parallel Road

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. When the vehicle is carried, such as on a ferry, and the vehicle itself is not running, the current vehicle position mark may be displayed in the position where the vehicle was until a measurement can be performed by GPS.
      Fig 4: [Identifying Current Vehicle Position Mark Displayed In Position Where Vehicle Was Until A Measurement Can Be Performed By GPS]

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   5. When the vehicle runs on a steep hill, the current vehicle position mark may deviate from the correct position.
      Fig 5: Identifying Deviation Of Current Vehicle Position Mark From Correct Position (When Vehicle Runs On Steep Hill)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   6. When the vehicle makes a continuous turn of 360, 720, 1,080, etc. degrees, the current vehicle position mark may deviate from the correct position.
      Fig 6: Identifying Deviation Of Current Vehicle Position Mark (When Vehicle Makes Continuous Turn Of 360, 720, 1,080 Degrees)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   7. When the vehicle moves erratically, such as constant lane changes, the current vehicle position mark may deviate from the correct position.
      Fig 7: Identifying Deviation Of Current Vehicle Position Mark (When Vehicle Moves Erratically)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   8. When the ignition switch is turned to the ACC or ON position on a turntable before parking, the current vehicle position mark may not point in the correct direction. The same will occur when the vehicle comes out of parking.
      Fig 8: Identifying Vehicle Position Mark Direction (When Ignition Switch Is Turned To ACC Or ON Position)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   9. When the vehicle runs on the snowy road or a mountain path with the chains installed or using a spare tire, the current vehicle position mark may deviate from the correct position.
      Fig 9: Identifying Vehicle Running On Snowy Road

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   10. When a tire is changed, the current vehicle position mark may deviate from the correct position.
   Fig 10: Changing Tire

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   • Diameter of the tire may change, causing a speed sensor error.
   • Performing the "tire change" in calibration mode will allow the system to correct the current vehicle position faster.

Conventionally, 2 separate devices, a "radio and display assy" and a "navigation ECU" are used. This model has adopted a new type, combining these devices into a single unit.

Fig 11: Radio And Navigation Assy Outline Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Vehicle position tracking methods

   It is essential that the navigation system correctly tracks the current vehicle position and displays it on the map. There are 2 methods to track the current vehicle position: autonomous (dead reckoning) and GPS* (satellite) navigation. Both navigation methods are used in conjunction with each other.

   *GPS (Global Positioning System)

   Fig 12: Identifying Vehicle Position Tracking Methods

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   OPERATION DESCRIPTION
   
   

   Operation	Description
   Vehicle Position Calculation	The navigation ECU calculates the current vehicle position (direction and current position) using the direction deviation signal from the gyro sensor and the running distance signal from the vehicle speed sensor and creates the driving route.
   Map Display processing	The navigation ECU displays the vehicle track on the map by processing the vehicle position data, vehicle running track, and map data from the map disc.
   Map Matching	The map data from the map disc is compared to the vehicle position and running track data. Then, the vehicle position is matched with the nearest road.
   GPS Correction	The vehicle position is matched to the position measured by GPS. Then, the measurement position data from the GPS unit is compared with the vehicle position and running track data. If the position is widely different, the GPS measurement position is used.
   Distance Correction	The running distance signal from the vehicle speed sensor includes the error caused by tire wear and slippage between the tires and road surface. Distance correction is performed to account for this. The navigation ECU automatically offsets the running distance signal to make up for the difference between it and the distance data of the map. The offset is automatically updated.

   HINT:

   The combination of autonomous and GPS navigation makes it possible to display the vehicle position even when the vehicle is in places where the GPS radio wave cannot receive a signal. When only autonomous navigation is used, however, the mapping accuracy may slightly decline.

   Fig 13: Identifying Autonomous And GPS Navigation

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Autonomous navigation

   This method determines the relative vehicle position based on the running track determined by the gyro and vehicle speed sensors located in the navigation ECU.

   1. Gyro sensor

      Calculates the direction by detecting angular velocity. It is located in the radio and navigation assy.

   2. Vehicle speed sensor

      Used to calculate the vehicle running distance.

3. GPS navigation (Satellite navigation)

   This method detects the absolute vehicle position using radio wave from a GPS satellite.

   *GPS satellites were launched by the U.S. Department of Defence for military purposes.

   Fig 14: Identifying GPS Navigation (Satellite Navigation)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   SATELLITE NUMBER - MEASUREMENT AND DESCRIPTION
   
   

   Number of satellites	Measurement	Description
   2 or less	Measurement impossible	Vehicle position cannot be obtained because the number of satellites is not enough.
   3	2-dimensional measurement is possible	Vehicle position is obtained based on the current longitude and latitude (This is less precise than 3-dimensional measurement).
   4	3-dimensional measurement is possible	Vehicle position is obtained based on the current longitude, latitude and altitude.

4. Map matching

   The current driving route is calculated by autonomous navigation (according to the gyro sensor and vehicle speed sensor) and GPS navigation. This information is then compared with possible road shapes from the map data in the map disc and the vehicle position is set onto the most appropriate road.

   Fig 15: Identifying Map Matching

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Touch switch

   Touch switches are touch-sensitive (interactive) switches operated by touching the screen. When a switch is pressed, the outer glass bends in to contact the inner glass at the pressed position. By doing this, the voltage ratio is measured and the pressed position is detected.

Fig 16: Vehicle Position Tracking Method - Touch Switch

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The navigation ECU uses a laser pickup to read the digital signals recorded on a DVD.

HINT:

• Do not disassemble any part of the navigation system.
• Do not apply oil to the navigation system.
• Do not insert anything but a DVD into the navigation system.

A CD player uses a laser pickup to read digital signals recorded on a CD. By converting the digital signals to analog, it can play music and other things. In general, CD players can play a 4.7-inch (12 cm) or 3.2-inch (8 cm) disc.

HINT:

• Do not disassemble any part of the CD player.
• Do not apply oil to the CD player.
• Do not insert anything but a CD into the CD player.

1. What is AVC-LAN?

   AVC-LAN, an abbreviation for "Audio Visual Communication Local Area Network", is a united standard developed by the manufacturers in affiliation with Toyota Motor Corporation. This standard pertains to audio and visual signals as well as switch and communication signals.

2. Purpose:

   Recently, car audio systems have rapidly developed and the functions vastly changed. The conventional car audio system is being integrated with multi-media interfaces similar to those in navigation systems. At the same time, customers are demanding higher quality from their audio systems. This is merely an overview of the standardization background. The specific purposes are as follows.

   1. To solve sound problems, etc. caused by using components of different manufacturers through signal standardization.
   2. To allow each manufacturer to concentrate on developing products they do best. From this, reasonably priced products can be produced.

HINT:

• If a short to B+ or short to ground is detected in the AVC-LAN circuit, communication is interrupted and the audio system will stop functioning.
• If an audio system is equipped with a navigation system, the multi-display unit acts as the master unit. If the navigation system is not equipped, the audio head unit acts as the master unit instead. If the radio and navigation assy is equipped, it is the master unit.
• The radio and navigation assy provides resistance to make communication possible.
• The car audio system with an AVC-LAN circuit has a diagnostic function.
• Each component has a specified number (3-digit) called a physical address. Each function has a number (2-digit) called a logical address.

1. Components of the audio system communicate with each other via the AVC-LAN.
2. The master component of the AVC-LAN is a radio and navigation assy with a 60 to 80 Ω resistor. This is essential for communication.
3. If a short circuit or open circuit occurs in the AVC-LAN circuit, communication is interrupted and the audio system will stop functioning.

1. The audio system has a diagnostic function (the result is indicated on the master unit).
2. A 3-digit hexadecimal component code (physical address) is allocated to each component on the AVC-LAN. Using this code, the component in the diagnostic function can be displayed.

1. The audio system has diagnostic function (The diagnostic result is displayed on the LCD of the radio and navigation assy). (Radio receiver with CD changer control function)
2. The component code (physical address), or three-digit number (in hexadecimal) is set for each component comprising AVC-LAN.
3. The logical address, or two-digit number (in hexadecimal) is set for each function and component unit in each component.

Fig 17: AVC-LAN Description

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002