Inspection Procedure 12

INSPECTION PROCEDURE 12: Noise Sometimes Appears on FM During Traveling.

DIAGNOSIS

STEP 1. Check the state of the antenna.

Check that there is no damage or crack in the roof antenna.

Q: Is the mast antenna assembled?

YES : Go to Step 2.

NO : Repair or replace the roof antenna.

STEP 2. The check after adjusting the radio.

Q: Readjust the radio. Is the noise eliminated?

YES : The procedure is complete.

NO : Go to Step 3.

STEP 3. Check with several broadcasting stations.

NOTE: Multipath noise and fading noise: Because of the frequency of FM waves in extremely high, it is highly susceptible to effects from geological formations and buildings. These effects disrupt the broadcast signal and obstruct reception in several ways.

Multipath noise
- This describes the echo that occurs when the broadcast signal is reflected by a large obstruction and enters the receiver with a slight time delay relative to the direct signal (repetitious buzzing).

Fading noise
- This is a buzzing noise that occurs when the broadcast beam is disrupted by obstructing objects and the signal strength fluctuates intricately within a narrow range.

Q: Is the abnormality in reception generated only within a certain range?

YES : The effect of an electrical field condition (multipath noise, fading noise) could be the cause. The procedure is complete.

NO : Go to Step 4.

STEP 4. Check that noise appears when the radio switch is turned on while the vehicle is stopped.

NOTE: Static electricity noise: Body static electric from the shock absorber rubber bushings used to prevent vibration, tires, etc. occurs because of separation from the earth, causing a buzzing noise. There is no measures to discharge the static electricity of the vehicle body. Check that there is no noise.

Q: Does noise appear when the radio switch is turned on while the vehicle is stopped and the radio is tapped while tuned away from a station?

YES : Go to Step 5.

NO : It may be static electricity noise. The procedure is complete.

STEP 5. Check that the radio is correctly earthed.

The radio is connected to the earth with an assembling screw.

Q: Is the radio correctly earthed?

YES : Go to Step 6.

NO : Tighten the screw securely.

STEP 6. Check by replacing the radio and CD player.

Q: Are operations normal when using another radio and CD player?

YES : Either repair or replace the radio and CD player.

NO : Repair or replace the roof antenna.