NO.3 NOISE FROM RADIO (FM ONLY)

id0903a1804500

Possible cause

• Antenna rod not installed.
• Jamming from aftermarket electronic equipment. (two-way radio, navigation system, mobile phone, etc.)
• Noise from electrical system on vehicle. (e.g. fuel pump)
• Battery malfunction.
• Charging system malfunction.
• Audio unit malfunction.
• Antenna plug poor connection.
• Antenna feeder malfunction.
• Electronic jamming from outside, or inferior condition of broadcasting station radio wave.
• Antenna installation loosened
Note

• FM broadcast has feature "sound quality is good" and "resistant to noise", but FM broadcast has particular noises. Though audio unit is designed to reduce noise, there are times noise occurs due to conditions.

Diagnostic procedure

STEP

INSPECTION

ACTION

1
• Tune to local broadcasting station and check reception condition.
• Is reception okay?
Yes
Tune to correct frequency of broadcasting station.
If not preset, preset it.
No
Go to the next step.
2
• Inspect antenna rod condition.
• Is antenna rod installed?
Yes
Go to the next step.
No
Advise customer to install antenna rod when radio is used.
3
• Is aftermarket electronic equipment (two-way radio, navigation system, mobile phone, etc.) installed?
Yes
Go to the next step.
No
Go to the Step 5.
4
• Remove aftermarket electronic equipment.
• Turn audio unit ON and check reception condition.
• Is reception improved?
Yes
The system is normal. (Explain to customers that aftermarket electronic equipment is cause of noise)
No
Go to the next step.
5
• Measure battery voltage.
• Is battery voltage okay?

Standard

With ignition switch ON: 11.5V or more

At idling: 12.5V or more

Note

• Inspect that battery cables are connected to terminals securely.

Yes
Go to the next step.
No
Charge battery. Inspect charging system, and repair or replace if necessary.
6
• Is noise occurring only when vehicle electrical system (e.g. fuel pump) operates?
Note

• Identify subject electrical component by disconnecting fuse, turning switch ON & OFF, or disconnecting & connecting connector.

• It will be easy when simulation function on WDS is used.

Yes
Go to the next step.
No
Go to the Step 8.
7
• Inspect power supply, ground condition, and noise prevention capacitor for electrical component.
• Is noise present after inspection?
Note

• Power supply to electrical component for voltage drop (compare with battery voltage)

• Resistance between ground of electrical component and body. (Should be close to 0ohm)

• Installation condition of noise prevention capacitor for fuel pump etc.

Yes
Go to the next step.
No
Troubleshooting completed.
8
• Inspect antenna plug connection condition.
• Is connection okay?
Yes
Go to the next step.
No
Insert antenna plug securely.
9
• Turn ignition switch to LOCK position.
• Measure continuity between antenna feeder axis and ground.
• Is there any continuity?
Yes
Replace antenna feeder.
No
Go to the next step.
10
• Compare reception with other audio unit on same model (model/unit) under same problem conditions.
• Is reception equivalent between customers unit and compared unit?
Yes
The system is normal (It is caused by electronic jamming from outside, or inferior broadcasting station signal condition.
No
Go to the next step.
11
• Retighten ground fixation for antenna installation part and antenna amplifier. Retighten antenna rod.
Note

• Refer to 0920 Center roof antenna inspection

• Is noise present, after retightening?
Note

• When antenna is not grounded perfectly, FM particular noise is likely to be conspicuous.

Yes
Replace audio unit.
No
Troubleshooting completed.