Mitsubishi Evolution X. Manual - part 997

RADIO AND CD PLAYER

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CHASSIS ELECTRICAL

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STEP 2. Check the external sound input mode.
Check if the external sound input mode of the radio and CD 
player is set.
Q: Is the check result normal?

YES : Go to Step 3.
NO :  Set the external sound input mode.

STEP 3. Check the audio adapter.
Check if the audio adapter is normal. (Refer to 

P.54A-365

.)

Q: Is the check result normal?

YES : Go to Step 4.
NO :  Replace the Audio adapter.

STEP 4. Check audio adapter connector C-125 and radio 
and CD player connector C-109 for loose, corroded or 
damaged terminals, or terminals pushed back in the 
connector.
Q: Are audio adapter connector C-125 and radio and CD 

player connector C-109 in good condition?
YES : Go to Step 5.
NO :  Repair or replace the damaged component(s) (Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

).

STEP 5. Check the wiring harness between audio adapter 
connector C-125 (terminal 5, 4, 6) and radio and CD player 
connector C-109 (terminal 14, 13, 4).

• Check the communication lines for open circuit and short 

circuit.

Q: Is the wiring harness between audio adapter connector 

C-125 (terminal 5, 4, 6) and radio and CD player 
connector C-109 (terminal 14, 13, 4) in good condition?
YES : Replace the audio adapter, and go to Step 6.
NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary.

STEP 6. Retest the system.
Check that the external input is normal.
Q: Is the check result normal?

YES : The trouble can be an intermittent malfunction (Refer 

to GROUP 00 

− How to use 

Troubleshooting/inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-15

).

NO :  Replace the radio and CD player.

RADIO AND CD PLAYER

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Inspection Procedure 7: Noise is present while moving (AM).

DIAGNOSIS

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 center.

NO : 

System is operating normally.

Inspection Procedure 8: 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 (12 − 16 miles) for stereo 

reception, and 30 

− 40 km (19 − 25 miles) for 

monaural reception.

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 AND CD PLAYER

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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.>

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 extends? 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 
center.

Inspection Procedure 9: 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 
generator.

DIAGNOSIS

STEP 1. Check the vehicles lighting system.

Q: Does the noise disappear when the vehicles 

headlights 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 

center.

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 

center.

NO : 

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

RADIO AND CD PLAYER

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Inspection Procedure 10: Noise is overpowering both AM and FM.

DIAGNOSIS

STEP 1. Check the state of the antenna.

Q:  Is the antenna assembled?

YES : 

Go to Step 2.

NO : 

Assemble the antenna. Check to see that 
the noise is gone.

STEP 2. 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 3.

When the engine is running : 

Check the vehicle's 

noise suppressor. (Refer to Inspection 
Procedure 12 

P.54A-353

).

STEP 3. 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 

center.

NO : 

Go to Step 4.

STEP 4. Verify that the radio is correctly 
grounded
The radio is connected to the ground with an assem-
bling screw.

Q: Is the radio correctly grounded?

YES : 

Go to Step 5.

NO : 

Consult the radio manufacturer's service 
center.

STEP 5. Check the connection of the antenna 
plug and radio and CD player.

Q:  Is the antenna plug thoroughly connected to the 

radio and CD player?
YES : 

Go to Step 7.

NO : 

Go to Step 6.

STEP 6. 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 

center.

NO : 

Go to Step 7.

STEP 7. 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 

center.

NO : 

Either repair or replace the antenna 
assembly. Check to see that the noise is 
gone.

Inspection Procedure 11: Excessive noise on AM and FM.

.

DIAGNOSIS

Radio reception can be affected by Radio Frequency 
(RF) emissions from a variety of sources. The distur-
bance is even greater if the station is weak or poorly 
tuned. FM reception is not as sensitive to distur-
bances as AM. AM reception is sensitive to electrical 
disturbances such as power lines, lightening and 
other types of similar electrical phenomena.

STEP 1. Check if the customer heard the noise 
under any of the following conditions.

• A motorcycle was passing.

• Lighting was flashing.

• Passed beneath a power line.

• Passed beneath a telephone line.

• Passed by a signal generator.

• Passed by any other sources of electrical noise.

• Passed under a bridge or through a tunnel.

Q: Did the noise occur during any of the 

circumstances listed above?
YES : 

The observed noise is normal.

NO : 

Go to Step 2.