Inspection Procedure 13

Noise Sometimes Appears on FM During Traveling.

DIAGNOSIS

STEP 1. Check the state of the antenna.

Q: Is the roof antenna pole assembled?

YES: Go to Step 2.

NO: Assemble the roof antenna pole. Check that there is no noise.

STEP 2. Check after adjusting the radio.

Q: Readjust the radio. Is the noise eliminated?

YES: Check that there is no noise.

NO: Go to Step 3.

STEP 3. Check with several broadcasting stations.

NOTE: Multipath noise and fading noise: Because the frequency of FM waves is 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 signal 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. Check that there is not noise.

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 ground, causing a buzzing noise. There are 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.

STEP 5. Check that the radio is correctly grounded.
The radio is connected to the ground with an assembling screw.

Q: Is the radio correctly grounded?

YES: Go to Step 6.

NO: Tighten the screw securely. Check that there is no noise.

STEP 6. Check by replacing radio and CD player.

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

YES: Replace the radio and CD player. Check that there is no noise.

NO: Either repair or replace the antenna assembly. Check that there is no noise.