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.
PARKING SYSTEMS
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 ve-
hicles, pickup trucks, and minivans that
are larger and generally sit higher than a
traditional automobile, driver-assistance
systems are one of the more common op-
tions. These vehicles have a larger blind
spot in the rear of the vehicle, making
it much more difcult to see the area
behind. Vehicle makers have added op-
tional convenience systems to assist the
driver in being aware of any obstructions
when backing up or driving.
There are two basic types of parking as-
sist systems: the sensor type that alerts
CALIBRATING DRIVER-ASSISTANCE SYSTEMS
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 ob-
ject is in a pre-determined distance from
the rear bumper. Generally, the vehicle
maker repair manuals will have measure-
ments 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 calibra-
tion 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.
SIDE ASSIST SYSTEMS
The Audi Q7 has an optional feature that
alerts the driver when a vehicle is ap-
proaching from the rear that could poten-
tially be in the drivers blind spot. Radar
sensors that are attached to both the driver
and passenger side inner rear bumper cov-
er detect the presence of a fast-approach-
ing 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
June 11, 2007
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 1 There may be parking
assistance sensors or other sensors
located in the rear bumper cover,
as shown on this Audi Q7.
Figure 3 Lines on the screen guide
the driver into a parking place.
Photo courtesy of Audi of America
Technical Information For The Collision Industry passenger side mirror will illuminate. If
the turn signal switch is operated, another
LED will ash rapidly, indicating that it is
not safe to change lanes.
Following the removal of the rear bumper
cover, the radar sensors must be cali-
brated 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 ra-
dar signals will be broadcast at incorrect
angles to the vehicle and the system will
not perform as it was designed.
CONCLUSION
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 follow-
ing 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.
CALIBRATING DRIVER-ASSISTANCE SYSTEMS
Continued From Page 1
Figure 4 After repairs are completed
to the rear of this vehicle, the camera
is calibrated with a scan tool.
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