Toyota Sienna Service Manual: Identification of noise source
1. Radio Description
- Radio frequency band
- Radio broadcasts use the radio frequency bands
shown in the table below.
- Service area
- 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.
- 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
- 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.
- 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.
- Noise problem
Technicians must have a clear understanding about
each customer's noise complaint. Use the following
table to diagnose noise problems.
HINT:
If the noise does not match the examples above, refer to the
descriptions about phasing and multipath.
1 VEHICLE BROUGHT TO WORKSHOP
2 INSPECT BATTERY VOLTAGE
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge or replace the battery
before proceeding.
3 BASIC INSPECTION
Turn ...
HINT:
Before inspecting the suspected areas listed in the table
below, check the fuse and relay.
Before inspecting the suspected areas listed in the table
below, check for DTCs.
...
Other materials:
Rear Occupant Classification Sensor LH Circuit
Malfunction
DTC B1782 Rear Occupant Classification Sensor LH Circuit
Malfunction
DESCRIPTION
The rear occupant classification sensor LH circuit consists of the occupant
classification ECU and the rear
occupant classification sensor LH.
DTC B1782 is recorded when a malfunction is detected in the rear oc ...
CD cannot be Inserted / Played or CD is Ejected Right After Insertion
INSPECTION PROCEDURE
1 CHECK IF A PROPER CD IS INSERTED
Make sure that the CD is an audio CD or a CD with an
MP3 or WMA file, and that it is not deformed, flawed,
stained, burred, or otherwise defective.
OK:
Normal CD
HINT:
Translucent or uniquely-shaped CDs cannot be
playe ...
Freeze frame data
1. DESCRIPTION
The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC
is stored. When troubleshooting, freeze frame data
can be helpful in determining whether the vehicle
was running or stopped, whether the engine was
warmed up or not, whe ...