Traffic Safety System: Overview — Saab 9-4X I (2011-2011)

Rear vision camera system, operation

The components used in the rear vision camera system are the camera, located at the rear of the vehicle, and the navigation radio.

When the vehicle is placed in REVERSE, the body control module sends a 12 V signal to the rear vision camera. This signal indicates that rear vision camera operation is required. Upon receipt of this signal, the camera will begin the power up cycle. A serial data message is also received by the navigation radio indicating the vehicle is in REVERSE. Upon receipt of this message, the navigation radio will also begin a power up cycle for the display. The rear vision camera transmits the video signal to the navigation radio through discrete + and - signal circuits. A metallic foil encases the video signal circuits and is tied to a shield ground circuit. This shield is designed to reduce electronic interference which may degrade the video signal and cause a distorted or otherwise degraded image.

If desired, the rear vision camera may be manually disabled through the navigation system menu. Refer to the navigation system owners manual for instructions on manually disabling and enabling the rear vision camera system. The following conditions may cause a degraded rear vision camera image

Ice, snow, or mud has built up on the rear vision camera
Dark conditions
Extreme light conditions, such as glare from the sun or the headlights of another vehicle
Damage to the rear of the vehicle
Extreme high or low temperatures or extreme temperature changes

If a malfunction is detected in the system, Service Rear Vision Camera may be displayed on the navigation radio as an indicator to the customer that a problem exists that requires service.

Object Detection Description and Operation (UD5)

The ultrasonic parking assist system is designed to identify and notify the driver of an object in the vehicle path when moving forward or reversing at speeds of less than 8 km/h (5 MPH). The distance and location of the object is determined by 8 object sensors: 4 located in the rear bumper and 4 located in the front bumper. The parking assist system will notify the driver using an audible beep signal through the radio.

The parking assist system is made up of the following components

Parking assist control module
Front object alarm sensors
Rear object alarm sensors
Parking assist switch
Parking assist switch indicator

Parking Assist Operation

When an object is within the measuring range of the sensor, the ultrasonic pulse is reflected and is received by the sending or a neighboring sensor. The sensor converts this signal into a voltage signal and sends this signal to the parking assist control module. The parking assist control module evaluates the received sensor signals. As soon as an object is within the measuring range, the parking assist control module sends a message via CAN-Bus to the radio in order to give out the acoustic distance signal.

The parking assist system can detect objects greater than 7.6 cm (3 in) wide and 25.4 cm (10 in) tall. The system cannot detect objects below the bumper, underneath the vehicle. If an object is detected, one of the following will occur

The measuring range of the front object alarm sensors is between 30-120 cm (11.8-47.2 in). From a distance of 120 cm (47.2 in), the acoustic signal is active. The frequency of the beep sound increases with decreasing distance. From a distance less than 30 cm (11.8 in), the sound becomes continuous.
The measuring range of the rear object alarm sensors is between 30-250 cm (11.8-98.4 in). From a distance of 250 cm (98.4 in), the acoustic signal is active. The frequency of the beep sound increases with decreasing distance. From a distance less than 30 cm (11.8 in), the sound becomes continuous.

The parking assist can be activated and deactivated by pressing the parking assist switch. When REVERSE gear is selected, park assist automatically is engaged for both front and rear sensors. When the vehicle is put into DRIVE from REVERSE the front assist sensors will be active up to speeds of 8 km/h (5 MPH) to assist with parking maneuvers. Once the vehicle is above 8 km/h (5 MPH) the front sensors are disabled and will not be re-enabled until either REVERSE gear is selected or the parking assist switch is pressed to activate the system. Once the parking assist switch is pressed during a key cycle the front sensors become active at speeds under 8 km/h (5 MPH). If the park assist switch is pressed again in the same key cycle the message "Park assist OFF" will be displayed in the driver information center if the vehicle speed is under 8 km/h (5 MPH) and front sensors detect an object within 120 cm (47.2 in). The LED indicator on the parking assist switch provides the ON/OFF state of the system. If the indicator is ON, the system is active and ready to assist.

The parking assist control module carries out a self test and monitors the sensors for electrical and mechanical faults. Monitored is the power supply of each sensor and the sensor signals, which need to alter when the vehicle moves. If this is not the case, the sensor is acoustically blocked or faulty. Mud, ice and snow may cause obstruction of the function of the sensors. Besides that the parking assist control module checks whether the correct type of sensor is installed. If any of these tests fails, a DTC with corresponding symptom is set, the parking assist is deactivated and the parking assist indicator in the instrument panel cluster is activated.

Circuit/System Description

The object sensors are 3-wire sensors that are used to determine the distance between the vehicle and an object of interest. The parking assist control module supplies 8 V to the object sensors via the 8 V reference circuit and provides ground via the low reference circuit. The parking assist control module triggers the sensors in a sequential loop. After each sensor transmits, the parking assist control module uses the sensor echo received through the signal circuit to calculate the distance and position of an object.