Toyota Sequoia (2005). Manual — part 594
–
DIAGNOSTICS
NAVIGATION SYSTEM
DI–2171
2365
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 num-
ber (2–digit) called a logical address.
7.
Communication system outline
(a)
Components of the audio system communicate with each other via the AVC–LAN.
(b)
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.
(c)
If a short circuit or open circuit occurs in the AVC–LAN circuit, communication is interrupted and the
audio system will stop functioning.
8.
Diagnostic function outline
(a)
The audio system has a diagnostic function (the result is indicated on the master unit).
(b)
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.
DIDBS–01
Vehicle brought into a workshop
1. Diagnostic questioning and symptom confirmation
HINT:
Ask the customer about symptoms and confirm malfunctions.
Fill out the Customer Problem Analysis check sheet.
The screen displays nothing (Go to step 5, proceed
to ”BLACK SCREEN (NO IMAGE APPEARS ON
NAVIGATION/AUDIO SCREEN)”) P.
Other symptoms
2. Confirm the system normal condition
P.
Applicable (This is not a malfunction.)
Not applicable
3. Check the diagnostic trouble codes
HINT:
Even if the malfunction symptom is not confirmed, check the diagnostic trouble codes.
This is because the system stores past diagnostic trouble codes.
Refer to the detailed description on the diagnostic screen, as necessary.
A code is output
A code is not output (Go to step 5)
4. Diagnostic trouble code chart.
HINT:
Find the output code on the diagnostic trouble code chart.
Output the diagnostic trouble code (Go to step 7)
5. Problem symptoms table
HINT:
If the symptom does not recur and no code is output,
perform the symptom reproduction method.
There is an applicable symptom code in the table
(Go to step 7)
There is no applicable
symptom code in the
table
6. Check the ECU terminal arrangement based on the malfunction symptom
7. Circuit inspection and part inspection
8. Recheck the diagnostic trouble code
HINT:
After deleting the DTC, recheck the diagnostic trouble code.
9. Perform confirmation test
END
Items inside
are titles of pages in this manual,
with the page number in the bottom portion. See
the pages for detailed explanations.
P.
P.
P.
P.
P.
DI–2172
–
DIAGNOSTICS
NAVIGATION SYSTEM
2366
HOW TO PROCEED WITH TROUBLESHOOTING
DIDBT–01
/ /
/ /
I28194
Inspector’s name:
Customer’s Name
VIN
Production Date
Licence Plate No.
Odometer Reading
km
mile
Frequency Problem Occurs
Always
Intermittently ( times a day)
Brought in
Problem Symptom
DTC Check
1st time trouble code.
2nd time trouble code.
RADIO AND NAVIGATION SYSTEM Check Sheet
–
DIAGNOSTICS
NAVIGATION SYSTEM
DI–2173
2367
CUSTOMER PROBLEM ANALYSIS CHECK
DIDBU–01
30 kHz
300 kHz
3 MHz
30 MHz
300 MHz
LF
MF
HF
VHF
AM
FM
Frequency modulation
Frequency
Designation
Radio wave
Modulation
Amplitude modulation
BE2818
FM (Stereo)
FM (Monaural)
AM
BE2819
Ionosphere
Phasing:
DI–2174
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DIAGNOSTICS
NAVIGATION SYSTEM
2368
IDENTIFICATION OF NOISE SOURCE
Radio Description
(a)
Radio frequency band
Radio Broadcasts use the radio frequency bands shown in the table below.
LF: Low Frequency
MF: Medium Frequency
HF: High Frequency
VHF: Very High Frequency
(b)
Service area
The service areas of the AM and FM broadcasts are vast-
ly different. Even if an AM broadcast has clear reception,
an FM broadcast originating in the same location may not
be received at all.
The service area of FM stereo broadcasts is small, and
static as well as interference (noise) easily enters the sig-
nal.
(c)
Radio reception problems
HINT:
In addition to static, other problems such as ”phasing”, ”multi–path”, and ”fade out” exist. These problems
are not caused by electrical noise, but by the radio signal propagation method itself.
(1)
Phasing
The AM frequency band reflects off the earth’s iono-
sphere at night. When this occurs, the reflected sig-
nal may interfere with the direct signal sent by the
same transmitter. This phenomenon is known as
”phasing”.
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