September 2023 - 20

need power to operate, they will indeed
generate heat. One test I have performed
in the past is by using a thermal camera
(Figure 4).
Say that you had a DTC related to a
particular sensor and you wanted to investigate
further. One way would be to activate
the sensors and look with a thermal
camera. If the faulty sensor demonstrated
a similar heat signature as the others that
were operating normally, then one could
assume that the sensor was receiving
power and ground and therefore could
proceed to focus on the signal circuit.
Another test that can be performed is
p Figure 3 - Ultrasonic sensors - Ford
Photo courtesy of Scott Brown
ULTRASONIC SENSORS
Ultrasonic sensors (Figure 3) operate based
on the principles of sound waves and their
interactions with objects in the environment
within their vicinity. It uses the timeof-flight
method to measure the distance
between the sensor and the target object(s).
Primarily, the ultrasonic sensor consists
of a piezoelectric transducer. This
device can convert electrical energy
into mechanical vibrations, therefore,
creating sound waves. When an electric
signal is applied to the piezo transducer,
it vibrates at a high frequency, typically
above 20,000 hertz which happens to be
classified as the " ultrasonic " range.
The emitted sound waves travel through
the air until they encounter an object in
their path. When the sound waves hit the
object's surface, they reflect or echo. Some
of the sound waves bounce back towards
the sensor where it is captured.
Signal reception is captured by the
receiver, which is another piezoelectric
transducer. This receiver is designed to
detect the echoes of the sound waves
that have bounced back from the object.
Then, the receiver transducer converts
the received sound waves into electrical
signals. The sensor's electronic circuits
use time-of-flight to calculate distance.
This time interval is often noticeably
short, measured in microseconds.
ULTRASONIC SENSOR
DIAGNOSTICS
Since multiple sensors are installed on
the vehicle and their location needs to be
known by the domain controller, proper
sensor setup needs to be performed whenever
replacement or service is required.
In most cases, a scan tool and service
information can guide you toward an
accurate diagnosis. However, there may
be other ways to assess some of the operational
characteristics. Since the sensors
to simply use a listening device such as
a stethoscope with only a hose attached
to listen to the chirps. Another test could
be to use a lab scope and an inexpensive
microphone probe to have a look as shown
in Figure 5 where I'm using the AESwave
uScope and a parking sensor detector
probe (microphone) to see the signal.
RADAR SENSORS
An automotive forward-facing radar sensor
is designed to detect and track objects
in front of a vehicle, providing crucial
information for various advanced driver
assistance systems (ADAS) and autonomous
driving features.
p Figure 4 - Ultrasonic sensors - FLIR E5 Infrared Camera
Photo courtesy of Scott Brown
20 PTEN SEPTEMBER 2023 www.VehicleServicePros.com
http://www.VehicleServicePros.com
September 2023

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