Mitsubishi Galant (2004+). Manual — part 1487

RADIO WITH CD PLAYER

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CHASSIS ELECTRICAL

54A-191

INSPECTION PROCEDURE 10: 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 WITH CD PLAYER

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CHASSIS ELECTRICAL

54A-192

INSPECTION PROCEDURE 11: 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-194

).

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

center.

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
center.

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

center.

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

center.

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-190

.) <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

center.

NO :

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

RADIO WITH CD PLAYER

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CHASSIS ELECTRICAL

54A-193

INSPECTION PROCEDURE 12: 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.

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.

RADIO WITH CD PLAYER

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CHASSIS ELECTRICAL

54A-194

INSPECTION PROCEDURE 13: 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.

NOTE: Voltage surges can be induced in the electri-
cal system by the collapse of a field (i.e. When power
is removed from the coil in an A/C compressor
clutch). This induced voltage surge will radiate a
Radio Frequency (RF) signal that is picked up by the

audio unit. In the case of the compressor clutch a
"pop" will be heard through the speakers. The capac-
itor, installed on this vehicle, will store the excess
voltage and prevent the production of RF noise. This
is because the capacitor will charge and discharge
as the voltage fluctuates. This has the effect of
"attracting" noise and bleeding it to ground without
interfering with the normal flow of current through the
system.

DESCRIPTION OF NOISE CONDITIONS

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.