Rear Parking Assist Sensor
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The parking assist sensors are located the in rear bumper of the vehicle. The sensors are used to determine the distance between an object and the rear bumpers. Each sensor emits an ultrasonic frequency which is reflected off object located behind the vehicle. These reflections are received by the sensors. The time difference between when the frequency was emitted and when the reflection is received, known as sensor ring time, is used to determine the distance to the object. The sensors report this information to the object alarm module.