Lexus RX300 (MCU15). Manual - part 151

I07329

Noise

I07330

Battery

Noise

Choke Coil

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BODY ELECTRICAL

AUDIO SYSTEM (Except Europe)

BE–151

LEXUS RX300   (RM785E)

(b)

Matters that require attention when checking:

S

Noise coming into the radio usually has no harm for
practical use as the noise protection is taken and it
is hardly thinkable for an extremely loud noise to
come in. When extremely loud noise comes into the
radio, check if the grounding is normal where the
antenna is installed.

S

Check if all the regular noise prevention parts are
properly installed and if there is any installation of
non–authorized  parts and non–authorized wiring.

S

If you leave the radio under out of tune (not tuning),
it is easy to diagnose the phenomenon as noise oc-
curs frequently.

(c)

Antenna and noise:
Electronic signal received by the antenna will reach to the
radio transmitting through the core wire of the coaxial
cable. Any noise wave other than radio wave is mixed into
this core wire, that naturally causes noise in the radio and
poor sound quality. In order to prevent these noises from
mixing into the radio, the core wire inside the coaxial cable
is covered with a mesh wire called shield wire. This shield
wire shelters the noise and transmits it to the ground, thus
preventing noise from mixing in.

If this shield wire has grounding failure, that causes noise.

(d)

Choke coil and noise:
The choke coil is connected in the rear window defogger
circuit. This is connected so to prevent noise from mixing
into the radio by making the noise current included in the
power source of the rear window defogger flow to the
ground.

N21547

Plug (Main)

Antenna
Terminal (Main)

Plug (Sub)

Antenna
Terminal (Sub)

1

2

3

4

N17398

Example :

Head

Capstan

Pinch Roller

BE4331

BE–152

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BODY ELECTRICAL

AUDIO SYSTEM (Except Europe)

LEXUS RX300   (RM785E)

(e)

Antenna code continuity check and grounding point:

HINT:
During troubleshooting, in case that the antenna code continu-
ity check, grounding check and grounding check of the choke
coil are needed.

Terminal connection

Normal condition

(1) ↔ (2)

Continuity

(3) ↔ (4)

No continuity

5.

COMPACT DISC PLAYER

Compact Disc (hereafter called ”CD”) Players use a laser beam
pick–up to read the digital signals recorded on the CD and re-
produce analog signals of the music, etc. There are 4.7 in. (12
cm) and 3.2 in. (8 cm) discs in the CD player.
HINT:
Never attempt to disassemble or oil any part of the player unit.
Do not insert any object other than a disc into the magazine.
NOTICE:
CD players use an invisible laser beam which could cause
hazardous radiation exposure. Be sure to operate the play-
er correctly as instructed.

6.

Tape Player/Head Cleaning:
MAINTENANCE

(a)

Raise the cassette door with your finger.
Next, using a pencil or similar object, push in the guide.

(b)

Using a cleaning pen or cotton applicator soaked in clean-
er, clean the head surface, pinch rollers and capstans.

7.

CD Player/Disc Cleaning:
MAINTENANCE

If the disc gets dirty, clean the disc by wiping the surface from
the center to outside in the radial directions with a soft cloth.
NOTICE:
Do not use a conventional record cleaner or anti–static pre-
servative.

I10058

Radio Receiver Assembly

Power Amplifier

CD Auto Changer

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BODY ELECTRICAL

AUDIO SYSTEM (Except Europe)

BE–153

LEXUS RX300   (RM785E)

8.

OUTLINE OF AVC–LAN

(a)

What is AVC–LAN?
AVC–LAN is the abbreviation, which stands for Audio Visual Communication–Local Area Network.
This is a unified standard co–developed by 6 audio manufactures associated with Toyota Motor Corpo-
ration.
The Unified standard covers signals, such as audio signal, visual signal, signal for switch indication
and communication signal.

(b)

Objectives
Recently the car audio system has been rapidly developed and functions have been changed drasti-
cally. The conventional system has been switched to the multi–media type such as a navigation sys-
tem. At the same time the level of customers needs to audio system has been upgraded. This lies be-
hind this standardization.
The concrete objectives are explained below.
(1)

When products by different manufactures were combined together, there used to be a case that
malfunction occurred such as sound did not come out. This problem has been resolved by stan-
dardization of signals.

(2)

Various types of after market products have been able to add or replace freely.

(3)

Because of the above (2), each manufacture has become able to concentrate on developing
products in their strongest field. This has enabled many types of products provided inexpensive-
ly.

(4)

Conventionally, a new product developed by a manufacture could not be used due to a lack of
compatibility with other manufactures products. Because of this new standard, users can enjoy
compatible products provided for them timely.

The above descriptions are the objectives to introduce AVC–LAN. By this standardization, development of
new products will no longer cause systematic errors. Thus, this is very effective standard for a product in the
future.
HINT:

S

When +B short or GND short is detected in AVC–LAN circuit, communication stops. Accordingly the
audio system does not function normally.

S

When audio system is not equipped with a navigation system, audio head unit is the master unit. (When
audio system is equipped with a navigation system, navigation ECU is the master unit.)

S

The car audio system using AVC–LAN circuit has a diagnosis function.

S

Each product has its own specified numbers called physical address. Numbers are also allotted to
each function in one product, which are called logical address.

BE1YP–01

BE–154

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BODY ELECTRICAL

AUDIO SYSTEM (Except Europe)

LEXUS RX300   (RM785E)

TROUBLESHOOTING

NOTICE:
When replacing the internal mechanism (computer part) of the audio system, be careful that no part
of your body or clothing comes in contact with the terminals of the leads from the IC, etc. of the re-
placement part (spare part).
HINT:
This inspection procedure is a simple troubleshooting which should be carried out on the vehicle during sys-
tem operation and was prepared on the assumption of system component troubles (except for the wires and
connectors, etc.).
Always inspect the trouble taking the following items into consideration.

S

Open or short circuit of the wire harness

S

Connector or terminal connection fault

Problem

No.

Radio

Radio not operating when power switch turned to ’ON’.

1

Display indicates when power switch turned to ’ON’, but no sound (including

’noise’) is produced.

2

Noise present, but AM – FM not operating.

3

Any speaker does not work.

4

Any AM or FM does not work.

5

Few preset turning bands.

5

Reception poor.

6

Sound quality poor.

7

Preset memory disappears.

8

Tape Player

Cassette tape cannot be inserted.

9

Cassette tape inserted, but no power.

10

Power coming in, but tape player not operating.

11

Any speaker does not work.

12

Sound quality poor.

13

Tape jammed, malfunction with tape speed or auto–reverse.

14

Cassette tape will not eject.

15

CD Auto Chenger

CD magazine cannot be inserted.

16

CD magazine inserted, but no power.

17

Power coming in, but CD player not operating.

18

Sound jumps.

19

Sound quality poor (Volume faint).

20

Any speaker does not work.

21

CD magazine will not be ejected.

22

Power Amplifier

No power coming in.

23

Power coming in, but power amplifier not operating.

24

Any speaker does not work.

25

Noise

Noise occurs

26

Noise produced by vibration or shock while driving.

27

Noise produced when engine starts.

28

The term ”AM” includes LW,MW and SW, and the term ”FW” includes UKW.