Toyota Tundra. Manual — part 137

Fig. 14: Identifying Phasing
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

2. Multipath

Multipath is a type of interference created when a vehicle receives 2 radio wave signals from
the same transmitter. One signal is reflected off buildings or mountains and the other signal is
received directly from the transmitter.

Fig. 15: Identifying Multipath
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

3. Fade out

Fade out is caused by objects (buildings, mountains, and other such large obstacles) that
deflect away part of a signal, resulting in a weaker signal when the object is between the
transmitter and vehicle. High frequency radio waves, such as FM broadcasts, are easily
deflected by obstructions. Low frequency radio waves, such as AM broadcasts, are much
more difficult to deflect.

Fig. 16: Identifying Fade Out
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

d. Noise problem

Technicians must have a clear understanding about each customer's noise complaint. Use the
following table to diagnose noise problems.

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Audio/Visual - Tundra

NOISE PROBLEMS DIAGNOSTIC CHART

HINT:

If the noise does not match the examples above, refer to the descriptions about phasing and
multipath.

PROBLEM SYMPTOMS TABLE

HINT:



Before inspecting the suspected areas listed in the table below, check the fuses and relays.



Before inspecting the suspected areas listed in the table below, check for DTCs.



Methods used to verify the cause of the problem are listed in order of probability in the suspected area
column.

Audio Function:

PROBLEM SYMPTOMS

Radio

Frequency

Noise Occurrence Condition

Presumable Cause

AM

Noise occurs in a specified area Foreign noise

AM

Noise occurs when listening to
an intermittent broadcast

An identical program transmitted from multiple
towers can cause noise where the signals overlap

AM

Noise occurs only at night

Music beat from a distant broadcast

FM

Noise occurs while driving in a
specified area

Multipath or phasing noise resulting from a
change in FM frequency

Symptom

Suspected Area

Refer To

Pressing power switch does not
turn on system.

Proceed to "Pressing Power
Switch does not Turn on System"

PRESSING POWER SWITCH

DOES NOT TURN ON SYSTEM

Radio receiver power source
circuit

RADIO RECEIVER POWER

SOURCE CIRCUIT

AVC-LAN circuit

AVC-LAN CIRCUIT

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

Panel switch does not function.

Steering pad switch circuit

STEERING PAD SWITCH

CIRCUIT

AVC-LAN circuit

AVC-LAN CIRCUIT

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Audio/Visual - Tundra

No sound can be heard from
speakers. (Audio is mute.) (for
separate type amplifier system)

Radio receiver power source
circuit

RADIO RECEIVER POWER

SOURCE CIRCUIT

Proceed to "No Sound can be
Heard from Speakers"

NO SOUND CAN BE HEARD

FROM SPEAKERS

Stereo component amplifier
power source circuit

STEREO COMPONENT

AMPLIFIER POWER SOURCE

CIRCUIT

Proceed to "Sound Signal Circuit
between Radio Receiver and
Stereo Component Amplifier"

SOUND SIGNAL CIRCUIT

BETWEEN RADIO RECEIVER

AND STEREO COMPONENT

AMPLIFIER

Speaker circuit (Independent
Amplifier)

SPEAKER CIRCUIT

(INDEPENDENT AMPLIFIER)

Proceed to "Mute Signal Circuit
between Radio Receiver and
Stereo Component Amplifier"

MUTE SIGNAL CIRCUIT

BETWEEN RADIO RECEIVER

AND STEREO COMPONENT

AMPLIFIER

Stereo component amplifier

STEREO COMPONENT

AMPLIFIER

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

No sound can be heard from
speakers. (Audio is mute.) (for
built-in type amplifier system)

Radio receiver power source
circuit

RADIO RECEIVER POWER

SOURCE CIRCUIT

Proceed to "No Sound can be
Heard from Speakers"

NO SOUND CAN BE HEARD

FROM SPEAKERS

Speaker circuit (Built-in
Amplifier)

SPEAKER CIRCUIT (BUILT-

IN AMPLIFIER)

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

Sound quality is bad in all modes.
(Volume is too low.) (for separate
type amplifier system)

Proceed to "Poor Sound Quality in
All Modes (Low Volume)"

POOR SOUND QUALITY IN

ALL MODES (LOW VOLUME)

Speaker circuit (Independent
Amplifier)

SPEAKER CIRCUIT

(INDEPENDENT AMPLIFIER)

Proceed to "Sound Signal Circuit
between Radio Receiver and
Stereo Component Amplifier"

SOUND SIGNAL CIRCUIT

BETWEEN RADIO RECEIVER

AND STEREO COMPONENT

AMPLIFIER

Proceed to "Mute Signal Circuit
between Radio Receiver and
Stereo Component Amplifier"

MUTE SIGNAL CIRCUIT

BETWEEN RADIO RECEIVER

AND STEREO COMPONENT

AMPLIFIER

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Audio/Visual - Tundra

Stereo component amplifier

STEREO COMPONENT

AMPLIFIER

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

Sound quality is bad in all modes.
(Volume is too low.) (for built-in
type amplifier system)

Proceed to "Poor Sound Quality in
All Modes (Low Volume)"

POOR SOUND QUALITY IN

ALL MODES (LOW VOLUME)

Speaker circuit (Built-in
Amplifier)

SPEAKER CIRCUIT (BUILT-

IN AMPLIFIER)

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

ASL does not function, (for
separate type amplifier system)

Proceed to "Vehicle Speed Signal
Circuit between Stereo
Component Amplifier and
Combination Meter"

VEHICLE SPEED SIGNAL

CIRCUIT BETWEEN STEREO

COMPONENT AMPLIFIER

AND COMBINATION METER

ASL does not function, (for built-
in type amplifier system)

Proceed to "Vehicle Speed Signal
Circuit between Radio Receiver
and Combination Meter"

VEHICLE SPEED SIGNAL

CIRCUIT BETWEEN RADIO

RECEIVER AND

COMBINATION METER

External device sound cannot be
heard or sound quality is bad.
(Stereo jack is used.)

Radio receiver power source
circuit

RADIO RECEIVER POWER

SOURCE CIRCUIT

Proceed to "Sound Signal Circuit
between Radio Receiver and
Stereo Jack Adapter"

SOUND SIGNAL CIRCUIT

BETWEEN RADIO RECEIVER

AND STEREO JACK

ADAPTER

Stereo jack adapter (for Column
Shift Type)

STEREO JACK ADAPTER

ASSEMBLY (FOR COLUMN

SHIFT TYPE)

Stereo jack adapter (for Floor
Shift Type)

STEREO JACK ADAPTER

ASSEMBLY (FOR FLOOR

SHIFT TYPE)

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

Abnormal noise occurs, (for
separate type amplifier system)

Proceed to "Noise occurs"

NOISE OCCURS

Stereo component amplifier

STEREO COMPONENT

AMPLIFIER

Radio receiver (for Column Shift
Type)

RADIO RECEIVER (FOR

COLUMN SHIFT TYPE)

Radio receiver (for Floor Shift
Type)

RADIO RECEIVER (FOR

FLOOR SHIFT TYPE)

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Audio/Visual - Tundra