Ford has published a servive procedure for this. It's special service mesaage 19121. It appears to be a very minor issue. Here's the text of the message for you - SOME 2005-2006 ESCAPE HYBRIDS BUILT FROM 8/2/2004 TO 11/21/2005 AND 2006 MARINERHYBRIDS BUILT FROM 10/1/2005 TO 11/21/2005 MAY EXHIBIT A SQUEAKING, SQUEALING ORGRINDING NOISE FROM THE REAR BRAKES WHILE DRIVING. THIS CONDITION MAY BE DUE TO A MISADJUSTED PARKING BRAKE. IF THIS CONDITION IS PRESENT, CHECK THE AMOUNT OF THREAD PROTRUSION OF THE PARKING BRAKE CABLE ADJUSTER AT THE PARK BRAKE LEVER. SET THE ADJUSTMENT SO THAT THERE IS 10MM, PLUS OR MINUS 1MM FOR VEHICLES BUILT BEFORE 5/3/2005 AND 15MM PLUS OR MINUS 1MM FOR VEHICLES BUILT ON 5/3/2005 OR AFTER. IF THIS CONDITION PERSISTS AFTER ADJUSTMENT IT MAY BE NECESSARY TO CLEAN THE PARK BRAKE DRUM AND SHOES OF EXCESSIVE LINING BUILD-UP.