Q: My Mustang is making a squeaking/chirping sound when driving and or coasting. When I apply brakes, the sound stops. What is the problem?

Hey there. A possibility of the noise is lack of lubrication on the brake hardware. If you have rear disc brakes, it could be the pad(s) continuing to contact the rotor after you release the brakes which is due to a sticky caliper and or dry (unlubricated) torque plate bushings/sliding pins. If the noise is really not bearable, the brakes at the suspect wheel have to be thoroughly cleaned with brake cleaner and all moving parts lubricated with an appropriate high temperature grease. There is also the possibility that the pads have worn to the minimum extent in which case the brake pad wear indicators (if equipped) are contacting the rotor. If you would like to have this checked, a qualified professional from YourMechanic can inspect the noise in person and follow through with appropriate repairs.