Nissan Technical Advisor 6/28/2011This could be cause by brake rotor shield. The brake rotor shield is designed to keep rocks and other debris from contact with the brake rotor, although noise might be present at all speed but it's most noticeable at low speed. This shield is also designed with an added cooling feature that can direct air through the brake rotor when the vehicle is in motion. If this shield contacts the brake rotor it can cause a squeaking noise. To check for this condition inspect the shield and bend shield back into proper position away from the brake rotor.