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Hissing or Interference on Radio
Check the following in the event of hissing or interference with radio reception:
" Station tuning
" Mechanical damage to the antenna structure
" Power supply terminal Rad_On for the antenna amplifiers in the diversity module.
" Antenna connector at diversity module
" Diversity module connected to ground by securing screws
" Antenna connector on radio or navigation system.
The following measures have been taken in the E70 to minimize reception interference
of AM and FM stations:
" Tailgate connected to ground by the tailgate hinges with integrated ground straps
" Low-noise AM and FM antenna amplifiers with direct ground connection
" Ground connection on the left and right silencer
" Shielded Wave barrier.
The ground connection on the two silencers helps to suppress interference transmitted
from the engine compartment (ignition electronics) along the exhaust system.
The exhaust system is a wave guide and, if no ground straps are used, it carries high-fre-
quency interference to the rear end of the vehicle. At the end of the exhaust system, the
interference is radiated out and couples into the antenna structures located at the rear of
the vehicle. The ground straps on the silencers connect the interference to ground, there-
by suppressing the interference. These ground connections have already been fitted to
the BMW X5 (E53).
The shielded wave barrier connects to ground the
screen of the coaxial line between the head unit
and antenna diversity on the D-pillar. Interference
transmitted by the screen is therefore conducted
away to ground.
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E70 Audio Systems
CD Changer
If the eject button is no longer working, a CD can be ejected using the diagnostic tester. If
the CD is mechanically jammed in the drive, it is necessary to send in the CD changer.
When the MOST bus enters sleep mode, the contents of the CD that has been inserted
and read is stored inside the head unit. There is therefore no need for this data to be read
once more when the MOST boots up again. The data is not saved in the event of a low
voltage situation before the MOST has entered sleep mode or a voltage interruption with
the MOST active. For this reason, the contents of the inserted CDs have to be read once
more when the MOST boots up.
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E70 Audio Systems
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