Audio System Toyota Sequoia I

Note. For manufacturer's precautions, see BODY ELECTRICAL SYSTEM. For circuit isolation/troubleshooting, see AUDIO SYSTEM. For wiring diagram, see RADIO.

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1. Radio wave band The radio wave bands used in radio broadcasting are as follows. (Scheme 1)
2. Service area There are great differences in the size of the service area for AM and FM monaural. Sometimes FM stereo broadcasts cannot be received even through AM can be received very clearly. Not only does FM stereo have the smallest service area, but it also picks up static and other types of interference ("noise") easily.
3. Reception problems: Besides the problem of static, there are also the problems called "fading", "multipath" and "fade out". These problems are caused not by electrical noise but by the nature of the radio waves themselves. Fading: Besides electrical interference, AM broadcasts are also susceptible to other types of interference, especially at night. This is because AM radio waves bounce off the ionosphere at night. These radio waves then interfere with the signals from the same transmitter that reach the vehicle's antenna directly. This type of interference is called "fading". Multipath: One type of interference caused by the bounce of radio waves off of obstructions is called "multipath". Multipath occurs when a signal from the broadcast transmitter antenna bounces off buildings and mountains and interferes with the signal that is received directly. Fade Out: Because FM radio waves are of higher frequencies than AM radio waves, they bounce off buildings, mountains, and other obstructions. For this reason, FM signals often seem to gradually disappear or fade away as the vehicle goes behind a building or other obstruction. This is called "fade out".
4. Compact disc player: Compact Disc Players use a laser beam pick-up to read the digital signals recorded on the CD and reproduce analog signals of the music, etc.
5. Tape player/head cleaning: MAINTENANCE Raise the cassette door with your finger. Next, using a pencil or similar object, push in the guide. Using a cleaning pen or cotton applicator soaked in cleaner, clean the head surface, pinch rollers and capstans.
6. CD player/disc cleaning & maintenance: If the disc gets dirty, clean the disc by wiping the surface from the center to outside in the radial directions with a soft cloth.
7. Outline of AVC-LAN: 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 manufacturers associated with Toyota Motor Corporation. The Unified standard covers signals, such as audio signal, visual signal, signal for switch indication and communication signal. 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 have been upgraded. These factors caused a need for standardization. The concrete objectives are explained below. Before standardization, malfunctions occurred when products by different manufacturers were combined together, such as sound did not come out. This problem has been resolved by standardization of signals. With standardization, various types of after market products can be added or replaced without conflict. With standardization, each manufacturer has become able to concentrate on developing products in their strongest field, enabling a cost reduction for many types of products. Prior to standardization, a new product developed by a manufacturer could not be used due to a lack of compatibility with other manufacturer's products. Because of this new standard, users can enjoy compatible products provided for them in a timely cost efficient manner. 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 a very effective standard for products in the future. NOTE: When +B short or GND short is detected in AVC-LAN circuit, communication stops. Accordingly the audio system does not function normally. 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, radio receiver is the master unit.) The car audio system using AVC-LAN circuit has a diagnosis function. 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 function: Error codes over tuner and connected equipment are displayed on the screen of tuner. Diagnosis mode Diagnosis start-up: For shifting to diagnosis mode, push "CD" switch 3 times with pressing "1" and "6" of PRESET switch at the same time while the audio power is OFF and ACC is ON. To exit from diagnosis mode, press "CD" switch for 2 seconds or turn the ignition key OFF. (When "1-190" is displayed, the mode is transferred to LAN check mode.) LAN check When starting up the diagnosis mode, the mode turns to LAN check mode, the screen displays the code numbers (physical address) of tuner and connected equipment. Smaller codes are displayed in order, displayed code numbers are switched by operating SEEK "UP" or "DOWN" switch. In LAN check mode, by pressing "5" of PRESET switch for more than 2 secs., diagnosis memory of each equipment can be deleted, when deletion is completed, the mode returns to LAN check mode. System check When pressing "1" of PRESET switch in LAN check mode, the mode turns to the system check mode, the system performs self diagnosis of connected equipment and displays the results. ("SYS" (showing the system is under detection) is displayed.) Perform the operation shown in the following illustration, then read the result of the inspection. NOTE: It sometimes takes approximately 40 seconds until the system inspection is completed. (Scheme 11) is an example of when diagnosis code "21" appears on the physical address (190) equipment. (ROM error occurs on the radio receiver.) The smaller code numbers (physical address) are displayed in order (code No., diagnosis code, support code of diagnosis code (object equipment)). When no error is detected in the system, "00" is displayed. When an error code is detected, up to 6 codes per one system are displayed. Pressing SEEK "UP" or "DOWN" switches the display. In the system check mode, when pressing "6" of PRESET switch the mode returns to LAN check mode. Diagnosis memory In LAN check mode, when pressing "2" of PRESET switch the mode turns to the diagnosis memory mode. ("CODE" is displayed.) The results of self diagnosis performed over tuner and connected equipment are memorized and displayed. NOTE: The smaller code numbers (physical address) are displayed in order (code No., periodic communication number when error occurs, diagnosis code, and support code of diagnosis code (object equipment)). When no error is detected in the system, "00" is displayed. When an error code is detected, up to 6 codes per one system are displayed. Pressing SEEK "UP" or "DOWN" switches the display. Each diagnosis code is same as code in the system check mode. When pressing "6" of PRESET switch, the mode returns to LAN check mode. (Scheme 12) is an example of when diagnosis code "D1" appears on the code (190) and (360) equipment. (Communication error occurs between the radio receiver and CD changer.) Perform the operation (Scheme 12), then read the result of the inspection. Diagnosis memory clear: After error is fixed, start up the diagnosis mode. Continue pressing "5" of PRESET switch for 2 secs. (CLR is displayed.) Press the "2" of PRESET switch and transfer to the diagnosis memory mode and check that the normal code (00) is output.
2. Diagnosis Code List If there is "O" in the column of system check, an error can be detected when the mode is switched to the system check mode. If there is "O" in the column of diagnosis mode, each unit is monitoring whether or not it has failure. In case of detecting failure, it memorizes DTC.

Note. This inspection procedure is a simple troubleshooting which should be carried out on the vehicle during system operation and was prepared on the assumption of system component troubles (except for the wires and connectors, etc.).

Always inspect the trouble taking the following items into consideration.

1. Open or short circuit of the wire harness
2. Connector or terminal connection fault

COMPONENT/DESCRIPTION OF PROBLEM/TROUBLESHOOTING ISOLATION

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1. Radio no power coming in
2. Radio power coming on, but radio not operating
3. Radio noise present, but AM-FM not operating
4. Radio any speaker does not work
5. Radio either AM or FM does not work, reception poor (volume faint), few preset tuning bands
6. Radio sound quality poor
7. Radio cannot set station select button, preset memory disappears
8. Tape player cassette tape cannot be inserted
9. Tape Player cassette tape inserted, but no power
10. Tape Player power coming in, but tape player not operating
11. Tape player any speaker does not work
12. Tape player sound quality poor (volume faint)
13. Tape Player tape jammed, malfunction with tape speed or auto-reverse
14. Tape player APS, SKIP, RPT buttons not operating
15. Tape player cassette tape will not be ejected
16. CD Player CD cannot be inserted
17. CD Player CD inserted, but no power
18. CD Player power coming in, but cd player not operating
19. CD Player sound skips
20. CD Player sound quality poor (volume faint)
21. CD Player any speaker does not work
22. CD Player CD will not be ejected
23. Antenna; antenna-related
24. Noise produced by vibration or shock while driving
25. Noise produced when engine starts

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1. Inspect radio receiver assembly circuit (W/O Power Amplifier) : Disconnect the connectors from the radio receiver assembly, and inspect the connector on the wire harness side.
2. W/O Power Amplifier: (JBL MADE) INSPECT RADIO RECEIVER ASSEMBLY CIRCUIT Disconnect the connectors from the radio receiver assembly, and inspect the connector on the wire harness side. If the circuit is not as specified, inspect the circuits connected to other parts. NOTE: Check the wire harness between radio receiver assembly and the CD auto changer, between radio receiver assembly and power amplifier.
3. Inspect front power amplifier circuit : Disconnect the connector from power amplifier and inspect the connector on the wire harness side. If the circuit is not as specified, inspect the circuits connected to other parts.
4. Inspect rear power amplifier circuit : Disconnect the connector from power amplifier and inspect the connector on the wire harness side. If the circuit is not as specified, inspect the circuits connected to other parts.

See also:
• BODY ELECTRICAL SYSTEM
• AUDIO SYSTEM