About I-CAR - Current Events/News: e-newsletters: Advantage Online: June 11, 2007

Figure 1 - There may be parking assistance sensors or other sensors located in the rear bumper cover, as shown on this Audi Q7.

Figure 2 - The sensors on the rear bumper of this Volvo XC90 alert the driver of objects behind the vehicle via an audible tone.

Figure 3 - Lines on the screen guide the driver into a parking place. Photo courtesy of Audi of America

Figure 4 - After repairs are completed to the rear of this vehicle, the camera is calibrated with a scan tool.

CALIBRATING DRIVER-ASSISTANCE SYSTEMS

The damage report reads "repair rear bumper cover." This sounds fairly routine. Remove the cover from the vehicle, repair, refinish, and reinstall. Job complete, right? Not so fast. The fact is, some vehicles will require a trip to the dealership following the removal of the rear bumper cover or rear hatch. Why? Some of the new features that are integrated into the rear of the vehicle, including rear parking sensors, rear imaging cameras, and other driver-assistance systems may require a calibration procedure following removal of the rear bumper cover or rear hatch (see Figure 1). The recalibration procedure may be required any time the rear cover has been removed, regardless of whether it has been damaged.

An article in the I-CAR Advantage Online on April 4, 2005, Parking Assist Systems, discussed parking assist sensors and how parking assist systems operate. With the increased number of sport-utility vehicles, pickup trucks, and minivans that are larger and generally sit higher than a traditional automobile, driver-assistance systems are one of the more common options. These vehicles have a larger blind spot in the rear of the vehicle, making it much more difficult to see the area behind. Vehicle makers have added optional convenience systems to assist the driver in being aware of any obstructions when backing up or driving.

There are two basic types of parking assist systems: the sensor type that alerts the driver through an audible tone (see Figure 2), and an imaging-type that has a camera located on the rear of the vehicle that displays what is behind the vehicle on an LED screen on the center console or dash. The parking assist sensors found on many vehicles typically use ultrasonic sensors that alert the driver when an object is in a pre-determined distance from the rear bumper. Generally, the vehicle maker repair manuals will have measurements for the height of the sensors. Other than making sure the sensor is working and that it is at the correct height, there will generally not be additional calibration requirements for this type of parking assist system. The imaging type of system may require a calibration procedure. These systems may have a parking feature that guides the driver into the parking place (see Figure 3). If the camera is out of calibration, there is a possibility that the vehicle will collide with another vehicle or object when parking.

The Audi Q7 has an optional feature that alerts the driver when a vehicle is approaching from the rear that could potentially be in the driver's "blind" spot. Radar sensors that are attached to both the driver and passenger side inner rear bumper cover detect the presence of a fast-approaching vehicle. The sensors are positioned at a 22° angle. This allows the radar signal to be broadcast rearward and into the adjacent lanes of travel. If a vehicle is detected in the blind spot, a light-emitting diode (LED) located on either the driver or passenger side mirror will illuminate. If the turn signal switch is operated, another LED will flash rapidly, indicating that it is not safe to change lanes.

Following the removal of the rear bumper cover, the radar sensors must be calibrated with the use of an Audi scan tool and some specialty equipment, including a Doppler generator, laser targets, and a calibration board (see Figure 4). With the exception of the Doppler generator, this same equipment is required for the calibration of the rear-imaging camera. If the calibration is not completed, the radar signals will be broadcast at incorrect angles to the vehicle and the system will not perform as it was designed.

Impacts to the rear of a vehicle have become more complex. When analyzing damage, it is a good idea to identify these options, and be aware that some systems may require a trip to a dealership following the repairs.

For comments or suggestions on the Advantage Online, please contact I-CAR Senior Instructional Designer Bob Jansen at bob.jansen@i-car.com.

Current Events/News: Advantage Online: 2007 Archives