Toyota Sequoia (2005). Manual - part 594

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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. 

DI–2214

Other symptoms

2. Confirm the system normal condition
P. 

DI–2162

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. 

DI–2191

P. 

DI–2214

 – 

DI–2294

P. 

DI–2203

P. 

DI–2184

P. 

DI–2199

DI–2172

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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

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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”.