Toyota Sienna Service Manual: Identification of noise source
1. Radio Description
- Radio frequency band
![Radio Description](images/books/424/62/index298.jpg)
- Radio broadcasts use the radio frequency bands
shown in the table below
- Service area
![Radio Description](images/books/424/62/index299.jpg)
- 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.
- 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.
![Radio Description](images/books/424/62/index21.jpg)
- 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.
![Radio Description](images/books/424/62/index22.jpg)
- 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.
![Radio Description](images/books/424/62/index23.jpg)
- Fade out
Fade out is caused by objects (buildings,
mountains, and other 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.
- Noise problem
Technicians must have a clear understanding about
each customer's noise complaint. Use the following
table to diagnose noise problems.
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 |
HINT:
If the noise does not match the examples above, refer to the
descriptions about phasing and multipath.
1 VEHICLE BROUGHT INTO A WORKSHOP
2 DIAGNOSTIC QUESTIONING AND SYMPTOM CONFIRMATION
Ask the customer about symptoms and confirm
malfunctions.
3 CONFIRM THE SYSTEM NORMAL CONDITION
4 CHECK D ...
1. CHECK NORMAL CONDITION
If the symptom is applicable to any of the following,
it is intended behavior, and not a malfunction.
Symptom
Answer
A longer route ...
Other materials:
Selecting the audio
source
Switching between audio sources such as radio and CD are
explained in this section.
Changing audio source
Press the “AUDIO” button to display the audio source selection
screen.
If the audio source selection screen is not displayed, press the “AUDIO”
button again.
Select the des ...
Vehicle exterior
Items
Check points
Doors
Do the doors operate smoothly?
Engine hood
Does the engine hood lock system work
properly?
Fluid leaks
There should not be any signs of fluid
leakage after the vehicle ha ...
Disposal
HINT:
When scrapping a vehicle equipped with the SRS or
disposing of the steering pad, be sure to deploy the airbag
first in accordance with the procedure described below. If any
abnormality occurs with airbag deployment, contact the
SERVICE DEPT. of TOYOTA MOTOR SALES, U.S.A., INC.
CAUTION:
...