Mitsubishi Montero Sport (2004+). Manual - part 559

RADIO AND TAPE PLAYER

TSB Revision

CHASSIS ELECTRICAL

54-223

STEP 4. Check that the antenna plug is properly 
connected to the radio.

Q: Is the antenna plug properly connected to the 

radio?

YES : 

Go to Step 7.

NO : 

Go to Step 5.

STEP 5. Check 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. Check that the antenna is in good 
condition and is 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. On a 
vehicles with a motor antenna, check the 
antenna. (Refer to Inspection Procedure 34 or 
35.)
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 8.) <Noise 
(hissing) occurs in weak signal areas such as moun-
tainous 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 that the noise is 
eliminated. If the noise is not eliminated, 
consult the radio manufacturer's service 
center.

RADIO AND TAPE PLAYER

TSB Revision

CHASSIS ELECTRICAL

54-224

INSPECTION PROCEDURE 8: There is More Noise on either AM or FM.

.

DIAGNOSIS
There is much noise only on AM. Due to differences 
in AM and FM systems, AM is more susceptible to 
noise interference.

STEP 1. Check that there is noise under the 
following state(s).

• A motorcycle was passing.

• Lighting was flashing.

• A vehicle passed close by, but it appeared to be a 

vehicle generating a particularly large amount of 
noise radiation.

• Passed beneath a power line.

• Passed beneath a telephone line.

• Passed close by a signal generator.

• Passed close by some other sources of electrical 

noise.

• Passed under a bridge.

Q: Is there noise in the above states?

YES : 

Go to Step 3.

NO : 

Go to Step 2.

STEP 2. Continue to check for static; when static 
is detected, check for the conditions listed 
above.

Q: Is there noise in the state described in Step 1?

YES : 

Noise prevention on the radio side is 

difficult. If the problem is particularly worse 
than other radios, consult a service center.

NO : 

Go to Step 3.

STEP 3. Check noise prevention on the radio side 
is difficult.
NOTE: Noise encountered during FM reception only. 
Due to differences in FM and AM systems, 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 8.) <Noise 
(hissing) occurs in weak signal areas such as moun-
tainous regions, but this is not due to a problem with 
the radio.> 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. 

Q: Is the noise level worse than other radios?

YES : 

Consult a service center. 

NO : 

If the noise level is roughly the same as 
other radios, there is no action to be taken.

RADIO AND TAPE PLAYER

TSB Revision

CHASSIS ELECTRICAL

54-225

INSPECTION PROCEDURE 9: There is Noise when Starting the Engine.

.

DIAGNOSIS

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.

NOTE: Capacitor: The capacitor does not pass DC 
current, but as the number of waves increases when 
it passes AC current, impedance (resistance against 
AC) decreases, and current flow is facilitated. A 
noise suppressing capacitor which take advantage of 
this property is inserted between the power line for 
the noise source and the ground. This suppresses 
noise by grounding the noise component (AC or 
pulse signal) to the body of the vehicle.

NOTE: Coil: The coil passes DC current, but imped-
ance rises as the number of waves increases relative 
to the AC current. A noise suppressing coil which 
takes advantage of this property is inserted into the 
power line for the noise source, and works by pre-
venting the noise component from flowing or radiat-
ing out of the line.

NOISE TYPE SOUNDS 
ARE IN PARENTHESES

CONDITION

CAUSE

REMEDY

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

• Increasing the engine 

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

• Disappears when the 

ignition switch turned 
to "ACC" position. 

• Mainly due to the 

spark plugs

• Due to engine noise

• Check or replace the 

ground cable. (Refer 
to figure 1, 2, 3 and 4) 

• Check or replace the 

noise capacitor. (Refer 
to figure 5.) 

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.

RADIO AND TAPE PLAYER

TSB Revision

CHASSIS ELECTRICAL

54-226

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.

• Ground 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 
grounded.

NOISE TYPE SOUNDS 
ARE IN PARENTHESES

CONDITION

CAUSE

REMEDY

AC002805

(FIGURE 1)

AB

AC002807

(FIGURE 2)

AB

AC002806

(FIGURE 3) <RWD>

AB

AC002808

(FIGURE 4) <4WD>

AB

AC002809

(FIGURE 5)

AB