2003 Hyundai Santa Fe Noise

Wow, what a head puzzler! I am still suspicious of brake pad and rotor interaction. How long has this symptom been occurring? Verify proper caliper operation. If this were my car, I would remove the rear brake pads, use an abrasive disk on a drill and clean all rotors surfaces to remove any glazing and create a crosshatch-effect that allows the pads to grip. (Make sure to do both sides of each rotor). Then use a 120 grit and sand off the face of the pads, so you have all-new surfaces. Use brake clean to remove all scale and debris on the rotor surfaces, and compressed air to remove all brake dust from the pads. Once this is done, it should remove the brake pads and rotors from being the source of your noise. Sometimes braking surfaces are tricky; rotor surfaces can cause noise without visual clues.