Theory Of Operation
The parking assist system may be classified as:
- Four-channel system
- Eight-channel system
According to the system type, the vehicle may have four sensors (four-channel system) located in the rear bumper or eight sensors (eight-channel system) located in the rear and front bumpers of the vehicle. The sensors send ultrasound waves when the vehicle is travelling forwards or backwards at low speed. The sensors send and receive ultrasonic waves from the echo coming back from any objects placed in the path of the vehicle. The control unit processes data from the sensors and performs a data triangulation to determine the relative distance, depending on the time elapsed between the output signal and the return signal. Optical obstacle approach warnings are provided on the 6.5" or 8" display to inform the driver that an object is nearby.
The Park Assist Module (PAM) has the following characteristics:
- It has two or three connectors, depending on if it is a 4- or 8-channel system
- It provides power to and receives signals from the ultrasonic sensors
- It manages operation based on the presence of a trailer
- It communicates and transmits data over the high-speed CAN-C2 network
If a factory tow hook (receiver hitch) is present, a message is sent from the trailer tow module (TTM) over the bus to the PAM when a trailer harness is connected to the vehicle. The PAM will disable the sensors if there is a trailer being used. To ensure the proper operation of the system when the trailer is not attached to the vehicle, the PAM control unit changes the sensor detection area range in order to take into account the space occupied by the tow hook. The ultrasonic sensor technology is based on the use of piezoelectric transducers which are able to both transmit and receive. The transducer generates and emits an ultrasonic wave that is reflected by an obstacle and is received by the transducer. The ultrasonic sensor is an active type which, in addition to the transducer, contains electronics able to drive, amplify and filter the received signal and to perform an analog/digital conversion to communicate with the PAM control unit. The park assist system may be activated through the switch located in the headlamp switch assembly; and when enabled, the LED in the switch illuminates.