Ford 2006 Focus Owner's Manual page 216

Accessories
• To avoid interference with other vehicle functions, such as anti-lock
braking systems, amateur radio users who install radios and antennas
onto their vehicle should not locate the Amateur Radio Antennas in
the area of the driver's side hood.
• Electrical or electronic accessories or components that are added to
the vehicle by the authorized dealer or the owner may adversely affect
battery performance and durability.
216
2006 Focus (foc)
Owners Guide (post-2002-fmt)
USA (fus)