Lexus Navigation System - Diagnostics: Overview Lexus GX J120

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1. Navigation system outline 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) 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. 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. Gyro sensor Calculates the direction by detecting angular velocity. It is located in the radio and navigation assy. Vehicle speed sensor Used to calculate the vehicle running distance. 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. NUMBER OF SATELLITES MEASUREMENT 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. 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.
2. DVD (Digital Versatile Disc) player outline (for navigation map) 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 ECU. Do not apply oil to the navigation ECU. Do not insert anything but a DVD into the navigation ECU. CAUTION: Do not look directly at the laser pickup because the navigation system uses an invisible laser beam. Be sure to only operate the navigation system as instructed.
3. Multi-display outline 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.
4. AVC-LAN Description 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. Purpose: Recently, car audio systems have rapidly developed and the functions vastly changed. The conventional car audio system is being integrated with multimedia 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. To solve sound problems, etc. caused by using components of different manufacturers through signal standardization. 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 receiver 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.
5. Communication system outline Components of the navigation system communicate with each other via the AVC-LAN. The radio receiver assy has enough resistance (60 to 80 ohm.) necessary for communication. If a short circuit or open circuit occurs in the AVC-LAN circuit, communication is interrupted and the navigation system will stop functioning.
6. Diagnostic function outline The audio system has a diagnostic function (the result is indicated on the master unit). 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.
7. Bluetooth outline Bluetooth is a new wireless connection technology that uses the 2.4 GHz frequency band. This makes it possible to connect a cellular phone (Bluetooth compatible phone*1) to the multi-display (the Bluetooth system is built in), and use a hands-free function with the cellular phone either in a pocket or bag. As a result, it is not necessary to use a connector attached directly to the cellular phone. *1: Some versions of Bluetooth compatible cellular phones may not function. HINT: The communication performance of Bluetooth may vary depending on obstructions or radio wave conditions between communication devices, electromagnetic radiation, communication device sensitivity, or antenna capacity.

DIAGNOSIS DISPLAY DETAILED DESCRIPTION

HINT

1. This part of the article contains a detailed description of displays within diagnostic mode.
2. Graphics may differ from the actual vehicle depending on the device settings and options. Therefore, some detailed areas may not be shown exactly the same as on the actual vehicle.

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1. System Check System Check Mode Screen Device Names and Hardware Address/*1 HINT: Registered device names are displayed. If a device name is unknown to the system, its physical address is shown instead. PHYSICAL ADDRESS DESCRIPTION Address No. Name Address No. Name 110 EMV 120 AVX 128 1 DIN TV 140 AVN 144 G-BOOK 178 NAVI 17C MONET 190 AUDIO H/U 1AC CAMERA-C 1B0 Rr-TV 1C0 Rr-CONT 1C2 TV-TUNER2 1C4 PANEL 1C6 G/W 1C8 FM-M-LCD 1D8 CONT-SW 1EC Body 1F0 RADIO TUNER 1F1 XM 1F2 SIRIUS 230 TV-TUNER 240 CD-CH2 250 DVD-CH 280 CAMERA 360 CD-CH1 3A0 MD-CH 17D TEL 440 DSP-AMP 530 ETC 5C8 MAYDAY 1A0 DVD-P 1D6 CLOCK 1F4 RSA 1F6 RSE 480 AMP - - Check Result/*2 HINT: Result codes for all devices are displayed. Code Clear/*3 Present DTCs are cleared. Memory Clear/*4 Present and past DTCs and registered connected device names are cleared. Diagnosis MENU Screen HINT: Each item is grayed out or not displayed based on the device settings. Unit Check Mode Screen Screen Description SCREEN DESCRIPTION Display Contents Device name/*1 Target device Segment/*2 Target device logical address DTC/*3 DTC (Diagnostic Trouble Code) Timestamp/*4 The time and date of past DTCs are displayed. (The year is displayed in 2 digit format.) Present Code/*5 The DTC output at the service check is displayed. Past Code/*6 Diagnostic memory results and recorded DTCs are displayed. LAN Monitor (Original) Check Result HINT: Check results of all the devices are displayed. LAN Monitor (Individual) Screen Screen Description SCREEN DESCRIPTION Display Contents Device name/*1 Target device Segment/*2 Target logical address DTC/*3 DTC (Diagnostic Trouble Code) Sub-code (device address)/*4 Physical address stored with DTC (If there is no address, nothing is displayed.) Connection check No./*5 Connection check number stored with DTC DTC occurrence/*6 Number of times the same DTC has been recorded
2. DISPLAY CHECK Vehicle Signal Check Mode Screen Screen Description HINT: Only items sending a vehicle signal will be displayed. This screen is updated once per second when input signals to the vehicle are changed.
3. NAVIGATION CHECK Navigation Check Screen HINT: Each item is grayed out or not displayed based on the device settings. GPS Information Screen Satellite information/* Information from a maximum of 12 satellites is displayed on the screen. This information includes the target GPS satellite number, elevation angle, direction and signal level. Receiving condition/*2 (DENSO model) DISPLAY CONTENTS DESCRIPTION Display Contents T The system is receiving a GPS signal, but is not using it for location. P The system is using the GPS signal for location. - The system cannot receive a GPS signal. (AISIN AW model) CONTENTS DISPLAY DESCRIPTION Display Contents 01H The system cannot receive a GPS signal. 02H The system is tracing a satellite. 03H The system is receiving a GPS signal, but is not using it for location. 04H The system is using the GPS signal for location. Measurement information/*3 CONTENTS DISPLAY DESCRIPTION Display Contents 2D 2-dimensional location method is being used. 3D 3-dimensional location method is being used. NG Location data cannot be used. Error Reception error has occurred. - Any other state. Position information/*4 CONTENTS DISPLAY DESCRIPTION Display Contents Position Latitude and longitude information on the current position is displayed. Date information/*5 CONTENTS DISPLAY DESCRIPTION Display Contents Date The date/time information obtained from GPS signal is displayed in Greenwich mean time (GMT). The last 4 digits are displayed.
4. Vehicle Sensors Screen Vehicle signal CONTENTS DISPLAY DESCRIPTION Display Contents REV/*1 REV signal ON/OFF state is displayed. SPD/*2 SPD signal condition is displayed. Sensor signal CONTENTS DISPLAY DESCRIPTION Display Contents Gyro sensor/*3 Gyro sensor output condition is displayed (when the vehicle runs straight or is stationary, the voltage is approximately 2.5 V). HINT: Signals are updated once per second only when vehicle sensor signals are changed.
5. Parts Information Screen Screen description CONTENTS DISPLAY DESCRIPTION Display Contents Navigation Manufacturer/*1 Navigation ECU manufacturer is displayed. Navigation Version No./*2 Navigation ECU version is displayed. Disc Manufacturer/*3 Map disc manufacturer is displayed. Disc Version No./*4 Map disc version is displayed.
6. Memory Copy/Paste Screen

HINT

This function cannot be used.

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1. CHECK NORMAL CONDITION If the symptom is applicable to any of the following, it is intended behavior, and not a malfunction. SYMPTOM SPECIFICATIONS 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. The following symptoms are not a malfunction, but are caused by errors inherent in the GPS, gyro sensor, speed sensor, and navigation ECU. The current position mark may be displayed on a nearby parallel road. Immediately after a fork in the road, the current vehicle position mark may be displayed on the wrong road. When the vehicle turns right or left at an intersection, the current vehicle position mark may be displayed on a nearby parallel road. 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. When the vehicle runs on a steep hill, the current vehicle position mark may deviate from the correct position. 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. When the vehicle moves erratically, such as constant lane changes, the current vehicle position mark may deviate from the correct position. 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. When the vehicle runs on a 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. When a tire is changed, the current vehicle position mark may deviate from the correct position. 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.

See also:
• TERMINALS OF ECU
• TERMINALS OF ECU
• PROBLEM SYMPTOMS TABLE