Mitsubishi Evolution X. Manual — part 998

RADIO AND CD PLAYER

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CHASSIS ELECTRICAL

54A-353

STEP 2. Compare the customers radio to another
identical model.
Operate the radio in a vehicle with a known good
audio system of the same type as the customer's.

Q: Is there more noise on the customers radio?

YES :

Check all power and ground connections. If

all connections are in good condition,
consult the radio manufacturers service
center.

NO :

The observed noise is normal.

Inspection Procedure 12: Noise is detected with engine running.

.

DIAGNOSIS

CAUTION

• Never connect a noise filter to the high ten-

sion cable (spark plug wire). Spark plug wires
incorporate resistors which have the effect of
suppressing noise. If a spark plug wire is
found to be causing noise, it must be
replaced.

• Confirm that the noise is not from an external

source.

• Noise prevention should be performed by

suppressing strong sources of noise first.

Description of noise

Condition

Cause

Solution

AM, FM: ignition noise
(popping, snapping,
cracking, buzzing)

• Increasing the engine

speed causes the
generator whine to
speed up and the
volume to decrease.

• Disappears when the

ignition switch turned
to "ACC", and engine
is off.

• Electrical interference

from the spark plugs.

• Engine noise.

• Check or replace the

ground cable.

• Check or replace

spark plug wires.

• Check or replace the

noise capacitor.

Other electrical
components

-

• Noise may intensify

due to aging electrical
components.

• Repair or replace the

electrical components.

Static electricity (cracking,
crinkling)

Noise disappears when
the vehicle is completely
stopped.

• Noise occurs when

parts or wiring move
and contact vehicle
body.

• Return parts or wiring

to their proper
position.

Static electricity (cracking,
crinkling)

• Various noises are

produced depending
on the body part of the
vehicle.

• This may be due to

the recent removal of
the front hood,
bumpers, exhaust
pipe and muffler,
suspension, etc.

• Properly ground parts.

• Properly ground all

body parts.

RADIO AND CD PLAYER

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CHASSIS ELECTRICAL

54A-354

Inspection Procedure 13: Noise appears during vibration or shocks.

DIAGNOSIS

STEP 1. Check the fit of the antenna.
Q: Is the antenna base fitted securely?

YES : Go to Step 2.
NO : Install the antenna, and tighten the mounting nut

(Refer to

P.54A-567

). Check that there is no noise.

STEP 2. Check the fit of antenna feeder cable.
Q: Is the antenna feeder cable fitted securely?

YES : Go to Step 3.
NO : Ensure that the antenna base and the radio and CD

player are fitted securely. Check that there is no
noise.

STEP 3. Check radio and CD player connector C-107,
C-109 and amplifier connector D-29, D-30 for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Are radio and CD player connector C-107, C-109 and

amplifier connector D-29, D-30 in good condition?
YES : Go to Step 4.
NO : Repair or replace the damaged component(s). Refer

to GROUP 00E, Harness Connector Inspection

P.00E-2

. Check that there is no noise.

AC705478

AC

Power steering
oil reservoir

Gtound cable

AC708951BK

C-109

Connectors: C-107, C-109

C-107

AC708954 AR

Connectors: D-29, D-30

D-30

D-29

RADIO AND CD PLAYER

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CHASSIS ELECTRICAL

54A-355

STEP 4. Check that noise appears when the radio switch is
turned on while the vehicle is stopped and the radio is
tapped while tuned away from a station.
NOTE: Body static electricity from the shock absorber rubber
bushings used to prevent vibration, tires, etc. occurs because
of separation from the ground, causing a buzzing noise. Since
no measures can be taken to discharge the static electricity of
the vehicle body. Check that there is no noise.
Q: Does noise appear when the radio switch is turned on

while the vehicle is stopped and the radio is tapped
while tuned away from a station?
YES : Go to Step 5.
NO : It may be static electricity noise.

STEP 5. Verify that the radio is correctly grounded.
The radio is connected to the ground with an assembling
screw.
Q: Is the radio correctly grounded?

YES : Go to Step 6.
NO : Tighten the screw securely. Check that there is no

noise.

STEP 6. Check by replacing radio and CD player.
Q: Do the other radio and CD player work normally?

YES : Either repair or replace the original radio and CD

player. Check that there is no noise.

NO : Either repair or replace the antenna assembly. Check

that there is no noise.

Inspection Procedure 14: Noise is present while moving (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 that there is
no noise.

STEP 2. Check the radio after adjusting it.

Q: Readjust the radio. Is the noise eliminated?

YES :

Check that there is no noise.

NO :

Go to Step 3.

STEP 3. Check with several broad casting.
NOTE: Multipath noise and fading noise: Because of
the frequency of FM waves in extremely high, it is
highly susceptible to effects from geological forma-
tions and buildings. These effects disrupt the broad-
cast signal and obstruct reception in several ways.

.

•

Multipath noise
This describes the echo that occurs when the
broadcast signal is reflected by a large obstruc-
tion and enters the receiver with a slight time
delay relative to the direct signal (repetitious
buzzing).

•

Fading noise
This is a buzzing noise that occurs when the
broadcast signal is disrupted by obstructing
objects and the signal strength fluctuates intri-
cately within a narrow range.

RADIO AND CD PLAYER

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CHASSIS ELECTRICAL

54A-356

Q: Is the problem station or location specific?

YES :

The effect of an electrical field condition

(multipath noise, fading noise) could be the
cause. Check that there is not noise.

NO :

Go to Step 4.

STEP 4. Check that noise appears when the radio
switch is turned on while the vehicle is stopped.
NOTE: Body static electricity from the shock
absorber rubber bushings used to prevent vibration,
tires, etc. occurs because of separation from the
ground, causing a buzzing noise. There is no mea-
sures to discharge the static electricity of the vehicle
body. Check that there is no noise.

Q: Does noise appear when the radio switch is turned

on while the vehicle is stopped and the radio is
tapped while tuned away from a station?
YES :

Go to Step 5.

NO :

It may be static electricity noise.

STEP 5. 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 6.

NO :

Tighten the screw securely. Check that
there is no noise.

STEP 6. Check by replacing radio and CD player.

Q: Do the other radio and CD player work normally?

YES :

Either repair or replace the original radio

and CD player. Check that there is no noise.

NO :

Either repair or replace the antenna
assembly. Check that there is no noise.

Inspection Procedure 15: Constant noise.

DIAGNOSIS

.

Use the Symptom Chart to diagnose the possible
cause(s) of the noise. Noise is often created by the
following factors:

• Traveling conditions of the vehicle

• Terrain of area traveled through

• Surrounding buildings

• Signal conditions

• Time period

If there are still problems with noise, even after per-
forming inspection procedures 7 to 14, obtain infor-
mation on the factors listed above. Determine
whether the problem occurs on AM or FM, the station
names, frequencies, etc. and contact the radio man-
ufacturer's service center.

Inspection Procedure 16: No reception (AM).

DIAGNOSIS

STEP 1. Check the state of the antenna.

Q: Is the antenna assembled?

YES :

Go to Step 2.

NO :

Assemble the antenna. The radio should
sound normally.

STEP 2. Check to see if inspections are taking
place is an area exposed to special electric
fields.

Q: Are inspections taking place under special electric

field conditions (underground garage, inside a
building, etc.)?
YES :

Go to Step 3.

NO :

Go to Step 4.

STEP 3. Move the vehicle and check the radio.
Move the vehicle to a good reception area that is not
exposed to special electric fields.

Q: Is reception of the strongest radio frequency

possible within the area?
YES :

There is no action to be taken.

NO :

Go to Step 4.