Inspection Procedure 11
Noise Sometimes Appears on FM during Traveling.Radio and CD Player Circuit
Refer to Radio and Tape Player
DIAGNOSIS
STEP 1. Retune the radio, and check that no noise?
Q: Does the problem clear up when returned?
YES: Check that there is no noise.
NO: Go to Step 2.
STEP 2. Check that the noise appears only in certain locations and only with certain 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: Does the problem appear only in certain locations and only with certain stations?
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 3.
STEP 3. Check that the connectors are properly connected.
NOTE: For the corresponding connectors, etc., refer to Radio and Tape Player
Q: Are the connector properly connected?
YES: Go to Step 4.
NO: Check the condition of the connector. Refer to Harness Connector Inspection. Check that there is no noise.
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 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.
STEP 5. Check that the radio is correctly.
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 that the antenna is correctly (If noise appears when the antenna is moved, this means the ground is not securely connected.)
Q: Is the antenna correctly grounded?
YES: Repair or replace the radio. Check that there is no noise.
NO: If rust is present on the antenna ground screw, clean off the rust and tighten the ground screw securely. Check that there is no noise.