See also:

Brakes
Occasional brake noise is normal. If a metal-to-metal, continuous grinding or continuous squeal sound is present, the brake linings may be worn-out and should be inspected by an authorized dealer. ...

Blocked sensor
An extreme build-up of materials on the left and/or right quarter panel fascias such as mud or snow can cause degraded performance of the BLIS . Also, heavy rain can cause the same effect. ...

Trailer tow false alerts
When towing a trailer, the sensors may detect the trailer thus causing a false alert. It may be desirable to turn the BLIS off if the false alerts become annoying. ...