Toyota Tundra. Manual — part 181

Fig. 135: Radio Frequency Reference Table
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

b. Service area

1. The service areas of AM and FM broadcasts are vastly different. Sometimes an AM

broadcast can be received very clearly but an FM stereo cannot. FM stereo has the smallest
service area, and is prone to pick up static and other types of interference such as noise.

c. Radio reception problems

HINT:

In addition to static, other problems such as "phasing", "multipath", and "fade out" exist. These
problems are not caused by electrical noise, but by the radio signal propagation method itself.

Fig. 136: Identifying Service Areas Of AM And FM Broadcasts
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

1. Phasing

AM broadcasts are susceptible to electrical interference and another kind of interference
called phasing. Occurring only at night, phasing is the interference created when a vehicle
receives 2 radio wave signals from the same transmitter. One signal is reflected off the
ionosphere and the other signal is received directly from the transmitter.

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Audio/Visual - Tundra

Fig. 137: 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. 138: 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. 139: 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 TABLE - AUDIO FUNCTION

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