change cables on iso

Just bought a new head unit and I remember reading somewhere that two cables need to be switched but not sure why.

Its a MK1 Octavia vRS I have.

I would search but not near a pc.

Thanks

Edit eh read the manual and it tells me to switch the red and yellow. Do I need to remove the blue cable for motor aerials?

Edited 30 December, 200817 yr by countryboyhaha