Audio System: Overview Lexus GS III

Scheme 1

1. What is AVC-LAN? AVC-LAN is the abbreviation, which stands for Audio Visual Communication-Local Area Network. This is a unified standard co-developed by 6 audio manufactures associated with Toyota Motor Corporation. The Unified standard covers signals, such as audio signal, visual signal, signal for switch indication and communication signal.
2. Objectives Recently the car audio system has been rapidly developed and functions have been changed drastically. The conventional system has been switched to the multi-media type such as a navigation system. At the same time the level of customers needs to audio system has been upgraded. This lies behind this standardization. The concrete objectives are explained below. When products by different manufactures were combined together, there used to be a case that malfunction occurred such as sound did not come out. This problem has been resolved by standardization of signals. Various types of after market products have been able to add or replace freely. Because of the above (2), each manufacturer has become able to concentrate on developing products in their strongest field. This has enabled many types of products provided inexpensively. Conventionally, a new product developed by a manufacture could not be used due to a lack of compatibility with other manufacturers products. Because of this new standard, users can enjoy compatible products provided for them timely.
3. The above descriptions are the objectives to introduce AVC-LAN. By this standardization, development of new products will no longer cause systematic errors. Thus, this is very effective standard for a product in the future.

HINT

1. When +B short or GND short is detected in AVC-LAN circuit, communication stops. Accordingly the audio system does not function normally.
2. When audio system is not equipped with a navigation system, audio head unit is the master unit. (When audio system is equipped with a navigation system, multi-display is the master unit.)
3. The car audio system using AVC-LAN circuit has a diagnosis function.
4. Each product has its own specified numbers called physical address. Numbers are also allotted to each function in one product, which are called logical address.

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1. Diagnosis start-up For shifting diagnosis mode, turn ignition switch ON and push the "DISC" switch 3 times while pressing "ch1" and "ch6" switches. HINT: To exit from the diagnosis mode, push the "DISC" switch for 1.7 sec. or turn ignition switch to OFF.
2. Service check mode After the diagnosis start-up, the system enters service check mode. Error codes over tuner and connected equipment are displayed on the screen of tuner. Results for each check are displayed as follows: good: No DTC is detected for both "System Check Confirmation" and "Diagnosis Memory Response". nCon: The Component does not respond to the "Diagnosis On Instruction" command. Applicable to only the system where connected components are limited to be used. ECHn: Application of new version has been confirmed by the "Diagnosis On Check", and there is one or more DTC which indicates "Replacement" in the "System Check Result Response" or "Diagnosis Memory Response". CHEC: Application of new version has been confirmed by the "Diagnosis On Check", and there is no DTC which indicates "Replacement" in the "System Check Result Response" or "Diagnosis Memory Response", but one or more DTC which indicated "Check" is identified. Old: Application of old version is confirmed by the "Diagnosis On Check", and DTC is identified in the "System Check Result Response" or "Diagnosis Memory Response". nrES: No response is identified to the "System Check Start Instruction" and "Request for System Check Result" commands. HINT: Check the present and past condition of components by performing the System Check and collecting stored DTC memories. Check results shall be displayed as one of six following indications: "good", "ECHn", "CHEC", "nCon", "Old" or "nrES".
3. Display Screen for Service Check. Example: Connection parts (physical address): Radio receiver (P190), CD Auto Changer (P360), MD changer (P3A0)
4. "ECHn" Detail Display Mode Screen
5. "CHEC" Detail Display Mode Screen
6. "Old" Detail Display Mode Screen