Inspection Procedure 8

Mixed With Noise, Only at Night (AM).

The following factors can be considered as possible causes of noise occurring at night.

1. Factors due to signal conditions: Due to the fact that long-distance signals are more easily received at night, even stations that are received without problem during the day may experience interference in a general worsening of reception conditions. The weaker a station is, the more susceptible it is to interference, and a change to different station or the appearance of a beating sound* may occur.

DIAGNOSIS

STEP 1. Check that the noise is still obvious even when the lights are off.

Q: Is the noise still obvious even when the lights are off?

YES: Go to Step 2.

NO: Go to Step 3.

STEP 2. Check with the following actions.

1. Tune to a station with a stronger signal.
2. Tune to a station with a stronger signal without completely extending the antenna (Whip antenna).

Q: Is there more noise than on the radio in other vehicles?

YES: Consult the radio manufacturer's service center.

NO: Check that there is no noise.

NOTE: Beat sound*: Two signals close in frequency interfere with each other, creating a repetitious high-pitched sound. This sound is generated not only by sound signals but electrical waves as well.

2. Factors due to vehicle noise: Generator noise may be a cause.

STEP 3. Check that the noise fades away when the vehicle harness is moved away from the radio (if the harness is not in the proper position).

Q: Does the noise fade away when the vehicle harness is moved any from the radio (if the harness is not in the proper position)?

YES: Consult the radio manufacturer's service center.

NO: If there is more noise than other radios, consult the radio manufacturer's service center.