NO.3 NOISE FROM RADIO (FM ONLY) [RADIO]

id0903e3804500

3 | Noise from radio (FM only)
--- | ---
Possible DTC | Using the M-MDS | U3000:04
Without using M-MDS (On-board diagnostic test mode) | 09:Er22
Possible cause | • Jamming from aftermarket electronic equipment (two-way radio, navigation system, mobile phone, etc.) • Battery malfunction • Noise from electrical system on vehicle (e.g. fuel pump) • Charging system malfunction • Electronic jamming from outside, or inferior condition of broadcasting station radio wave • Antenna plug poor connection • Antenna feeder malfunction • Antenna installation loosened • Audio unit malfunction 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 | • Can the location where the noise occurs be specified? | Yes | The system is normal. (Explain to the customer that the noise is caused by radio wave disturbances or broadcast wave conditions from the outside.)
No | Go to the next step.
2 | • 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.
3 | • Is aftermarket electronic equipment (two-way radio, navigation system, mobile phone, etc.) installed? | Yes | Go to the next step.
No | Go to 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? Specification: With ignition switch ON: 11.5 V or more At idling: 12.5 V 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 M-MDS is used. | Yes | Go to the next step.
No | Go to Step 8.
7 | • Inspect power supply, ground condition, and noise prevention capacitor for electrical component. • Is noise present after inspection? Note • Inspect following: ― Power supply to electrical component for voltage drop (compare with battery voltage) ― Resistance between ground of electrical component and body. (Should be close to 0 ohm) ― 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 the ignition switch to the OFF 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 customer’s unit and compared unit? | Yes | The system is normal (It is caused by electronic jamming from outside, or inferior broadcasting station signal condition).
No | Replace audio unit. (See AUDIO UNIT REMOVAL/INSTALLATION.)