Porsche 996 TT, Repair Manual

Page: 1785 / 2099

the outputs.
12. Is the voltage between 8.4
and 11.0V?
Radio function OK?
Check the audio connections (+)
and (−) for short circuits or ground
connections.
15. Check polarity of the entire wiring.
16. Repair any detected damage.
’ End
6 Is a short circuit present? Repair the cable connection and check
the system
’ End ’ Step 4
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Reduced sound quality in one or more loudspeakers
Note
Reduced sound quality may be accompanied by a humming noise. •
1. Switch on the system and change the fader and balance setting on the
radio.
2. Check the fault status.
3. Find out on which channels the problem occurs.
Work instruction Yes No
1 Switch the radio between FM,
AM, cassette and CD (depending
on the available components).
Does the problem occur in all
program sources?
Find out whether it is a question of
an objective fault (’ go to Step 2)
or a subjective perception (’ go to
Step 4) of the system behaviour. If the problem only occurs in
FM or AM radio reception,
check the reception. If the
problem persists, replace the
radio or CD player
’ End
2 Is a humming noise audible on
one channel?
Check the polarity of the cable
connection between the radio and
the Bose amplifier. Remedy any
possible problems. If the fault has
been remedied ’ End.
If the fault is still present ’ Step 3 ’ Step 3
3 Connect a functional radio/CD
player. Problem remedied?
Replace radio/CD player
’ End Connect a functional
amplifier
’ End
4 Carry out a comparative test with
a functional system.
System behaviour identical?
Involve the customer in the
comparative test.
Customer satisfied ’ End.
Customer not satisfied, consult
Porsche After Sales. ’ Step 3
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einordnung
Malfunctions in radio system 1722