1. Radio wave band
The radio wave bands used in radio broadcasting are as follows:
Lf: low frequency
mf: medium frequency
hf: high frequency
vhf: very high frequency
2. Service area
Not only does fm stereo have the smallest service area, but it also picks up static and other types of interference (”noise”) easily.
3. Reception problems
Hint
: besides the problem of static, there are also the problems called ”fading”, ”multipath” and ”fade out”. These problems are caused not by electrical noise but by the nature of the radio waves themselves.
4. Noise problems
Radio wave |
Condition in which noise occurs |
Probable cause |
Am | Noise occurs at a specific place. | Strong possibility of foreign noise. |
Noise occurs when listening to faint broadcasting. | The same program may be broadcasted from some local stations.
If the program is the same, one of those may be tuned in. |
|
Fm | Noise occurs only at night. | Strong possibility of beat from a distant broadcasting. |
Noise occurs at a specific place during driving. | Strong possibility of multipath noise and fading noise caused by changes of fm frequency. |
Hint
: if the condition where the noise occurs does not meet any of the above, find out the cause based on ”reception problems”. Refer to the description about multipath and fading mentioned previously. 5. Compact disc player
Hint
: never attempt to disassemble or oil any part of the player unit. Do not insert any object other than a disc into the magazine.
Notice
: cd players use an invisible laser beam which could cause hazardous radiation exposure. Be sure to operate the player correctly as instructed.
6. Maintenance
Tape player/head cleaning:
Using a pencil or similar object, push in the guide.
7. Maintenance
Cd player/disc cleaning:
If the disc gets dirty, clean the disc by wiping the surface from the center to outside in the radial directions with a soft cloth.
Notice
: do not use a conventional record cleaner or anti–static preservative.
8. Communication system
9. Diagnosis function
Cd sound skips
Inspection procedure
1 Disc cleaning
Disk cleaning
) if the disk gets dirty, clean the disk by wiping the surface
from the center to outside in the radial directions
with a soft cloth.
Notice:
do not use a conventional record cleaner or anti–static preservative.
Standard: m ...
Basic inspection
Resistance measuring condition of electronic parts
unless stated, all resistance is measured at an ambient
temperature of 20 c (68 °F). As the resistance
may be outside the specifications if measured at high temperatures
immediately after
the vehicle has been running, measur ...
Symptom confirmation and diagnostic trouble code
Hint:
the diagnostic system in corolla has various functions. The first
function is the diagnostic trouble
code (dtc) check, in which a malfunction in the signal circuits to the ecu
is stored in code form in
the ecu memory. Another function is the input signal check, which checks if
...