Mitsubishi L200. Manual - part 728

 

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Mitsubishi L200. Manual - part 728

 

 

RADIO AND CD PLAYER

CHASSIS ELECTRICAL

54A-279

Inspection Procedure 5: Noise appears at certain places when travelling.

DIAGNOSIS PROCEDURE

STEP 1. Check the noise occur when entering or 
near a particular structure (building, tunnel, 
mountain, etc).

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 2.

STEP 2. After taking the following measures to 
prevent the noise, check that no noise appears.
(1) Change to a different station with a stronger wave 

to boost resistance to interference.

(2) Suppress high tones to reduce noise.

Q: Do the following measures eliminate the noise?

YES : 

This diagnosis is complete.

NO : 

Go to Step 4.

STEP 3. Ask the owner about the state of the 
noise.
Find out the following information from the owner.

• Place where the noise occurs.

• Locality conditions (valley, mountain, etc).

• Name and frequency of stations affected by noise

Q: Which is the noise, vehicle noise or external 

noise?
Vehicle noise : 

It may not be possible to prevent 

noise if the signal is weak. This diagnosis is 
complete.

External noise : 

In almost all cases, prevention on 

the receiver side is impossible. Weak 
signals especially are susceptible to 
interference. Go to Step 4.

STEP 4. Check that there is no noise.

Q: Does noise still exist? 

YES : 

If there is more noise than on radios in other 

vehicles, 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.

NO : 

Normal.

Inspection Procedure 6: Mixed with noise, only at night.

The following factors can be considered as possible 
causes of noise appearing at night.
1. Factors due to signal conditions: Due to the fact 

that long-distance signals are more easily 
received at night, even stations that are received 
without problem during the day may experience 
interference in a general worsening of reception 
conditions. The weaker a station is the more 
susceptible it is to interference, and a change to 
different station or the appearance of a beating 
sound* may occur.
NOTE: Beat sound*: Two signals close in fre-
quency interfere with each other, creating a repeti-
tious high-pitched sound. This sound is generated 
not only by sound signals but electrical waves as 
well.

2. Factors due to vehicles noise: Alternator noise 

may be a cause.

DIAGNOSIS PROCEDURE

STEP 1. Check that the noise still obvious even 
when the lamps are off.

Q: Is the noise still obvious even when the lamps are 

off?
YES : 

Go to Step 2.

NO : 

Go to Step 3.

Step 2. Check hat the following actions.
Tune to a station with a stronger wave.

Q: Is there more noise than on radio in other 

vehicles?
YES : 

Consult the radio manufacturer's service 

centre.

NO : 

This diagnosis is complete.

RADIO AND CD PLAYER

CHASSIS ELECTRICAL

54A-280

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 : 

Repair the wiring harness.

NO : 

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

Inspection Procedure 7: Broadcasts can be heard but both AM and FM have a lot of noise.

DIAGNOSIS PROCEDURE

STEP 1. Check the state of the antenna.

Q:  Is the mast antenna assembled?

YES : 

Go to Step 2.

NO : 

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

STEP 2. Check 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 7 

P.54A-282

).

STEP 3. Check 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 4.

STEP 4. Check that the radio is correctly earthed
The radio is connected to the earth with an assem-
bling screw.

Q: Is the radio correctly earthed?

YES : 

Go to Step 5.

NO : 

Assemble the radio and CD player into the 
vehicle.

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. Check that the noise is eliminated when 
the antenna plug is properly attached.

Q: Is the noise eliminated?

YES : 

This diagnosis is complete.

NO : 

Go to Step 7.

STEP 7. Check 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 : 

Repair or replace the antenna. 

Inspection Procedure 7: Broadcasts can be heard but both LW/MW/FM have a lot of noise.

DIAGNOSIS PROCEDURE

STEP 1. Check the state of the antenna.

Q: Is the antenna assembled?

YES : 

Go to Step 2.

NO : 

Repair or replace the antenna.

STEP 2. Check 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?

RADIO AND CD PLAYER

CHASSIS ELECTRICAL

54A-281

When the engine is stopped : 

Go to Step 3.

When the engine is running : 

Check the vehicle's 

noise suppressor (Refer to Inspection 
Procedure 8 

P.54A-282

).

STEP 3. Check that the following actions 
disappear the noise.
(1) Tune to a station with a stronger wave.
(2) Extend the antenna completely (Pillar antenna).
(3) Adjust the sound quality to suppress high tones.

Q: Is the noise eliminated?

YES : 

This diagnosis is complete.

NO : 

Go to Step 4.

STEP 4. Check that the radio is correctly earthed
The radio is connected to the earth with an assem-
bling screw.

Q: Is the radio correctly earthed?

YES : 

Go to Step 5.

NO : 

Assemble the radio and CD player into the 
vehicle.

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. Check that the noise is eliminated when 
the antenna plug is properly attached.

Q: Is the noise eliminated?

YES : 

This diagnosis is complete.

NO : 

Go to Step 7.

STEP 7. Check 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 : 

Repair or replace the antenna. 

RADIO AND CD PLAYER

CHASSIS ELECTRICAL

54A-282

Inspection Procedure 8: There is noise when starting the engine.

DIAGNOSIS PROCEDURE

CAUTION

• Connecting a high tension cable to the noise 

filter may destroy the noise filter and should 
never be done.

• Check that there is no external noise. Since 

failure to do this may result in an incorrect 
diagnosis due to the inability to identify the 
noise source, this operation must be per-
formed.

• Noise prevention should be performed by 

suppressing strong sources of noise step by 
step.

Noise type sounds are in 
parentheses

Conditions

Cause

Remedy

AM/FM or FM/MW/LW: 
ignition noise (popping, 
snapping, cracking, 
buzzing)

• Increasing the engine 

speed causes the 
alternator whine 
sound to speed up 
and the volume to 
decrease

• Disappears when the 

ignition switch turned 
to "ACC". 

• Due to engine noise

• Check or replace the 

earth cable.

• Check or replace the 

noise capacitor.

Other electrical 
components

Noise may occur as the 
electrical components 
become older.

Repair or replace the 
electrical components.

Static electricity (cracking, 
crinkling)

• Disappears when the 

vehicle is completely 
stopped.

• Severe when the 

clutch is engaged

Occurs when parts or 
wiring move for some 
reason and contact metal 
parts of the body.

Return parts or wiring to 
their proper position.

Static electricity (cracking, 
crinkling)

• Various noise are 

produced depending 
on the body part of the 
vehicle.

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

Earth parts by bonding. 
Cases where the 
problem is not eliminated 
by a signal response to 
one area are common, 
due to several body parts 
being imperfectly 
earthed.

 

 

 

 

 

 

 

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