SYSTEM
Noise type
Sounds are in
these
Cause
Response
AM, FM: Ignition noise
l
Increasing the engine
l
Mainly due to the spark
l
Noise filter
[Popping,
speed causing the
plugs.
l
Noise condenser
Cracking,
ping sound to speed up,
l
Due to the engine noise.
l
Ground cable
and volume decreases.
l
Disappears when the
ignition switch is turned
to ACC.
Other electrical
Noise may appear as
Repair or replace electrical
nents
components become
components.
older.
Static electricity
l
Disappears when the
Occurs when parts or
Return parts or wiring to their
vehicle is completely
ing move for some reason
proper
position.
stopped.
and contact metal parts of
l
Severe when the clutch
the body.
is engaged.
Various noises are
Due to detachment from
Ground parts
by
bonding.
depending on the
the body of the front hood,
Cases where the problem is
body part of the vehicle.
bumpers, exhaust pipe and
not eliminated by a single
muffler, suspension, etc.
response to one area are
common, due to several body
parts
being imperfectly
grounded.
Caution
1.
Connecting a high tension cable to the noise
filter may destroy the noise filter and should
never be done.
2. Check that there is no external noise. Since
failure due this may result in misdiagnosis
due to inability to identify the noise source,
this operation must be performed.
3. Noise prevention should be performed by
suppressing strong sources of noise step by
step.
NOTE
1. Condenser
The condenser does not pass
D.C.
current, but
a s t h e n u m b e r o f w a v e s i n c r e a s e s w h e n i t
p a s s e s
c u r r e n t ,
impedance (resistance
2.
against A.C.) decreases, and current flow is
facilitated. A noise suppressing condenser
which takes advantage of this property is in-
serted between the power line for the noise
source and the ground. This suppresses noise
by grounding the noise component
or
pulse signal) to the body of the vehicle.
Coil
The coil passes D.C. current, but impedance
rises as the number of waves increases relative
to the A.C. current. A noise suppressing coil
which takes advantage of this property is in-
serted into the power line for the noise source,
and works by preventing the noise component
from flowing or radiating out of the line.
TSB Revision