Mazda CX-7 2007 Workshop Manual page 1451

NO.2 NOISE FROM RADIO (AM ONLY)[RADIO]
2 Noise from radio (AM only)/Possible DTC: 09:Er22
• 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
POSSIBLE
• Audio unit malfunction
CAUSE
• Antenna plug poor connection
• Antenna feeder malfunction
• Electronic jamming from outside, or inferior condition of broadcasting station radio wave
• Antenna installation loosened
Diagnostic procedure
STEP
• Tune to local broadcasting station and check
1
reception condition.
• Is reception okay?
• Inspect antenna rod condition.
2
• Is antenna rod installed?
• Is aftermarket electronic equipment (two-way
3
radio, navigation system, mobile phone, etc.)
installed?
Note
• TV antenna located closely to audio
antenna can be cause of noise. Relocate
TV antenna.
• Remove aftermarket electronic equipment.
4
• Turn audio unit ON and check reception
condition.
• Is reception improved?
• Measure battery voltage.
5
• 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.
• Is noise occurring only when vehicle
6
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.
• Inspect power supply, ground condition, and
7
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.
SYMPTOM TROUBLESHOOTING [RADIO]
INSPECTION
Yes Tune to correct frequency of broadcasting station.
If not preset, preset it.
No Go to the next step.
Yes Go to the next step.
No Advise customer to install antenna rod when radio is used.
Yes Go to the next step.
No Go to the Step 5.
Yes The system is normal. (Explain to customers that
aftermarket electronic equipment is cause of noise)
No Go to the next step.
Yes Go to the next step.
No Charge battery. Inspect charging system, and repair or
replace if necessary.
Yes Go to the next step.
No Go to the Step 8.
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.
id0903e3804400
ACTION
09-03E–5
09-03E