NO.2 NOISE FROM RADIO (AM ONLY) [RADIO]

id0903e3804400

2

Noise from radio (AM only)/Possible DTC: 09:Er22
POSSIBLE CAUSE
•  Glass antenna malfunction (damaged or not continuity)
•  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

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 the glass antenna.
•  Is the glass antenna normal?
Yes
Go to the next step.
No
Repair the glass antenna.
(See FILAMENT REPAIR.)
3
•  Is aftermarket electronic equipment (two-way radio, navigation system, mobile phone, etc.) installed?
Note
•  TV antenna located closely to audio antenna can be cause of noise. Relocate TV antenna.
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?
Standard
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.
Note
•  The audio unit supplies 12 V battery power to the antenna amplifier for the AM radio reception in the radio mode. The audio unit cannot receive the AM signals without the 12 V battery power to the antenna amplifier. If the AM signals become strong, the audio unit may receive the signal with noises.
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 customer’s unit and compared unit?
Note
•  Due to following differences, you may detect a difference in reception efficiency.
(Vehicle side factor)
―  Antenna installation location, height, feeder wiring routing, optional electrical equipment
(Audio unit factor)
―  Volume concern type: It decreases change of volume when signals become weak. (Noise is conspicuous)
―  Noise decrease type: It decreases volume when signals become weak, so that noise is not conspicuous.
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.
•  Is noise present, after retightening?
Yes
Replace the audio unit.
(See AUDIO UNIT REMOVAL/INSTALLATION.)
(See AUDIO UNIT DISASSEMBLY/ASSEMBLY.)
No
Troubleshooting completed.