Understanding The Park Assist System

Ultrasonic active park assist sensor, located on the lower half of the fender on a 2015 Ford F-150.

A key part of being able to diagnose a problem with advanced driver assistance systems (ADAS) is understanding how the system works. Knowing what is happening inside the system will help you properly diagnose why the system may be failing. This will prevent replacing parts that are not causing the system issue. Let’s take a look at the inner workings of a park assist system.

Park assist sensors are used for two different styles of systems, park assist and active park assist. Park assist uses sensors in the rear and/or front bumper covers to sense the distance between the vehicle and the object. Active park assist uses the same sensors in the front and rear bumpers; however, there are generally more sensors used. Park assist normally will only make a sound and/or show an image to tell the driver the distance to an object. Whereas active park assist will tap into other vehicle systems to physically park the vehicle. Normally, additional sensors are located in the sides of the bumper or in the fender.

The sensors that are used are generally ultrasonic sensors. An ultrasonic sensor uses soundwaves to detect the distance to an object. The sensor sends out and receives the soundwave after bouncing off a detected object. The time it takes for the soundwave to return determines the distance the object is from the sensor.

Most park assist systems have their own module that calculates the distance to the objects. Then, the module triggers a chime or communicates with another module to display an image on the driver information center. It may also send the signal to more than one computer to control the self-parking features. The park assist module is normally responsible for sending power to the park assist sensors, along with receiving the signal back.

Understanding how the system functions can shorten diagnostic times. Knowing what part of the system to test will help prevent installing parts that don’t actually fix the problem.

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