Mitsubishi 380. Manual — part 918

RADIO WITH CD PLAYER

CHASSIS ELECTRICAL

54A-206

STEP 19. Check the wiring harness between rear speaker
(RH) connector D-09 (terminals 1 and 2) and radio and CD
player connector C-111 (terminals 1 and 7).

NOTE: Also check intermediate connector C-28 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-28 is damaged, repair or
replace the connectors as described in GROUP 00E, Harness
Connector Inspection

P.00E-2

.

Q: Is the wiring harness between rear speaker (RH)

connector D-09 (terminals 1 and 2) and radio and CD
player connector C-111 (terminals 1 and 7) in good
condition?
YES : Replace the radio and CD player. The rear speaker

(RH) should sound.

NO : Repair the wiring harness. The rear speaker (RH)

should sound.

54DB041A

HARNESS SIDE

3

9

4

12

14

6

13

5

1110

8

2

7

1

CONNECTOR: C-111

16DB350A

CONNECTOR:C-28

16DB608A

CONNECTOR: D-09

HARNESS SIDE

RADIO WITH CD PLAYER

CHASSIS ELECTRICAL

54A-207

INSPECTION PROCEDURE 6: Noise is Present while Moving (AM).

STEP 1. Ask the driver about the noise.
(1) Find out the following information from the owner.
(2) Place where the noise occurs.
(3) Locality conditions (valley, mountain, etc).
(4) Name and frequency of stations affected by

noise.

Q: What type of noise is detected, vehicle noise or

external noise?
Vehicle noise :

It may not be possible to prevent

noise if the signal is weak. Go to step 2.

External noise :

In almost all cases, prevention on

the receiver side is next to impossible when
the signal is weak. Go to Step 4.

STEP 2. Ask the driver about the location where
the noise occurs.

Q: Does the noise occur when entering or near a

particular structure (building, tunnel, mountain,
etc)?
YES :

Go to Step 3.

NO :

Go to Step 4.

STEP 3. Check if the noise can be eliminated by
adjusting the radio.
(1) Adjust the radio as follows.
(2) Change to a different station with a stronger

signal. This will boost the systems resistance to
outside interference.

(3) Suppress high tones to reduce noise.

Q: Has the noise been eliminated?

YES :

The noise has now been eliminated. Inform

the customer that it is normal to hear noise
while receiving a weak station.

NO :

Go to Step 4.

STEP 4. Check for the noise.

Q: Does noise still exist?

YES :

If there is still more noise than on other

similar radio’s find out the type of noise. Ask
the owner for the name and frequency of the
affected stations, and consult with the radio
manufacturer service centre.

NO :

System is operating normally.

INSPECTION PROCEDURE 7: Noise is Present while Moving (FM).

.

DIAGNOSIS

NOTE: FM waves have the same properties as light,
and can be deflected and blocked. FM signal recep-
tion is severely degraded in the shadow of obstruc-
tions such as buildings or mountains. An FM receiver
will then only receive a reflected signal.

1. The signal becomes weak as the distance from

the station's transmission antenna increases. The
signal strength received depends on the signal
strength of the transmitting station and intervening
obstructions such as buildings and hills. Generally
speaking, the area of good reception is
approximately 20

− 25 km for stereo reception,

and 30

− 40 km for monaural reception.

2. The signal will becomes weak when an area of

shadow from the transmitting antenna (places
where there are obstructions such as mountains
or buildings between the station transmitter and
the vehicle), and noise will appear. <This is called
first fading, and gives a steady buzzing noise.>

ACX01869

10kW

OUTPUT FM

BROAD CAST

FOR STEREO:

20 - 25 km

(12 - 16 miles)

FOR MONAURAL:

30 - 40 km (19 - 25 miles)

FOR HOME STEREO:

80 - 90 km (50 - 56 miles)

MALTIPATH INTERFERENCE

FIRST FADING

INTERFERENCE

AC

RADIO WITH CD PLAYER

CHASSIS ELECTRICAL

54A-208

3. If a direct signal hits the antenna at the same time

as a signal reflected by obstructions such as
mountains or buildings, interference of the two
signals will generate noise. When moving, noise
will appear each time the vehicle's antenna
passes through this kind of obstructed area. The
strength and interval of the noise varies according
to the signal strength and the conditions of
deflection. <This is called multipath noise, and is a
repetitive buzzing.>

4. Since FM stereo transmission and reception has a

weaker field than monaural, it is often
accompanied by a hissing noise.

After taking measures to prevent the noise, check
that no noise occurs.
5. Change to a different station with a stronger wave

to boost resistance to interference.

6. Suppress high tones to reduce noise.

7. Does vehicle have an antenna which extend? If

not eliminate this step.

If there is noise, the following causes can be consid-
ered.
8. If due to vehicle noise: It may not be possible to

prevent noise if the signal is weak.

9. If due to external noise: In almost all cases,

prevention on the receiver side is not possible.
Weak signals especially are susceptible to
interference.

If there is more noise than on radios in other vehi-
cles, find out the noise condition and the name and
frequency of the receiving stations from the owner,
and consult with the radio manufacturer's service
centre.

INSPECTION PROCEDURE 8: Sound mixed with Noise, Only at Night (AM).

The following can be considered as possible causes
of noise appearing only at night.
1. It is significantly easier to receive long-distance

signals at night. This means that even stations
that are received without a problem during the day
may experience problems at night. Remember
that the weaker station is more susceptible to
interference. The appearance of a beat sound
may occur in the evening. A beat sound is created
when two signals close in frequency interfere with
each other. A common sign of this type of
interference is a repetitious high-pitched sound
that may over power the desired radio station.
This sound is generated not only by sound signals
but electrical waves as well.

2. The changing system may also be a source of

noise. When diagnosing radio noise, do not over
look the possibility of a problem with the vehicles
alternator.

DIAGNOSIS

STEP 1. Check the vehicles lighting system.

Q: Does the noise disappear when the vehicles

headlamps are turned "OFF"?
YES :

Go to Step 2.

NO :

Go to Step 3.

STEP 2. Check that the following actions
disappear the noise.
Tune to a station with a stronger signal.

Q: Is there more noise than on radio in other

vehicles?
YES :

Consult the radio manufacturer's service

centre.

NO :

Check that there is no noise.

STEP 3. Check that the noise fades away when
the vehicle harness is moved away from the
radio (if the harness is not in the proper
position).

Q: Does the noise fade away when the vehicle

harness is moved any from the radio (If the
harness is not in the proper position)?
YES :

Consult the radio manufacturer's service

centre.

NO :

If there is more noise than other radios,
consult the radio manufacturer's service
centre.

RADIO WITH CD PLAYER

CHASSIS ELECTRICAL

54A-209

INSPECTION PROCEDURE 9: Noise is Overpowering both AM and FM.

DIAGNOSIS

STEP 1. Verify that the noise occur when the
engine is stopped or the engine is running.

Q: Does noise occur when the engine is stopped or

the engine is running?
When the engine is stopped :

Go to Step 2.

When the engine is running :

Check the vehicle's

noise suppressor. (Refer to Inspection
Procedure 13

P.54A-210

).

STEP 2. Verify that the following actions
disappear the noise.
(1) Tune to a station with a stronger wave.
(2) Adjust the sound quality to suppress high tones.

Q: Is the noise eliminated?

YES :

Consult the radio manufacturer's service

centre.

NO :

Go to Step 3.

STEP 3. Verify that the radio is correctly
grounded

Q: Is the radio correctly grounded?

YES :

Go to Step 4.

NO :

Consult the radio manufacturer's service
centre.

STEP 4. Check the connection of the antenna
plug and radio and CD player or radio, CD player
and CD changer.

Q: Is the antenna plug thoroughly connected to the

radio and CD player or radio, CD player and CD
changer?
YES :

Go to Step 6.

NO :

Go to Step 5.

STEP 5. Verify that the noise is eliminated when
the antenna plug is properly attached.

Q: Is the noise eliminated?

YES :

Consult the radio manufacturer's service

centre.

NO :

Go to Step 6.

STEP 6. Verify that the antenna is in good
condition and is it properly mounted.

Q: Is the antenna in good condition and is it properly

mounted?
YES :

Consult the radio manufacturer's service

centre.

NO :

Go to Step 7.

STEP 7. Clean the antenna plug and ground wire
mounting area. Mount the antenna securely.

NOTE: Noise encountered during FM reception only
due to differences in FM and AM system, FM is not
as susceptible as AM to interference from engines,
power lines, lighting, etc. On the other hand, due to
the characteristics of FM waves, there are some-
times cases of noise or distortion which are gener-
ated by typical noise interference (first fading and
multipath). (Refer to Inspection Procedure 9

P.54A-207

.) <Noise (hissing) occurs in weak signal

areas such as mountainous regions, but this is not
due to a problem with the radio.>

NOTE: Furthermore, the amount of interference will
be comparatively less for vehicles equipped with a
diversity antenna system*. If there is an equivalent
amount of distortion in vehicles or radios of the same
type, then differences will be because of differences
in antenna systems, and this should be explained to
the user.

NOTE: Diversity antenna system*: A system where
two types of antenna (glass main antenna and glass
sub antenna) are equipped and the antenna that pro-
vides the best reception car be selected.

Q: Is the antenna in good condition?

YES :

Consult the radio manufacturer's service

centre.

NO :

Clean or repair it. Check the noise is
eliminated. If the noise is not eliminated,
consult the radio manufacturer's service
centre.