Park Distance Control
Park Distance Control
Introduction
Park Distance Control is a safety/convenience system that is an option on the E46. The system is carried over from the E39 and features the ultra-sonic sensors on the rear bumper only.
The sensors detect the close proximity to other objects when maneuvering the vehicle in tight spaces (such as parallel parking or parking in narrow garages spaces).
The driver is warned, through an audible tone (beeping), when the vehicle comes close to another object. As the distance to the object decreases, the beeping frequency increases until a steady tone is produced. As the distance to the object increases, the steady tone will return to a beep and stop when the vehicle moves away from the object.
The PDC is automatically switched ON when the ignition is switched on, however it does not become active until the vehicle is shifted into reverse.
PDC Components
The PDC consists of the following components:
PDC CONTROL MODULE - Mounted in the trunk on the right side above the battery.
The PDC control module activates the ultrasonic sensors mounted in the rear bumper cover. After activation, the module monitors the signals coming back through the sensors. Through this signal, the control module is able to determine the distance to any object close to the bumpers of the vehicle. As the vehicle comes close to an object, the control module will activate the acoustic warning through the right rear audio system speaker.
FOUR ULTRASONIC SENSORS - Mounted in the rear bumper. The sensors are small transmitter/receiver modules that are specifically designed for automotive use. The sensors are limited to the following angles of monitoring:
- 90° on the horizontal plane
- 60° on the vertical plane
Transmitting Mode
The control module sends a 40 Khz signal to the sensor and each sensor is then activated in a specific sequence (firing order). The ceramic element of the sensor vibrates and produces an ultrasonic sound wave that is sent out from the bumper.
Receiving Mode
If the sound wave contacts an object, the wave is bounced back to the sensor. The returning wave causes the ceramic element to vibrate creating an electrical signal as feedback to the control module.
The control module determines the distance to the object by the time difference between the sent signal and the received ultrasonic wave signals.
System Operation
When KL 15 is switched ON, the PDC system is switched "ON", in the standby mode. The system performs a self-check of the ultrasonic sensors and control electronics.
When the vehicle is shifted into reverse, the system is activated and the sensors are activated in the predetermined order.
If an object is detected within the operating range of one the sensors, a signal is sent to the PDC control module and the acoustic warning is generated. At the same time the control module checks the signals from the adjacent sensors to help determine the actual distance to the object.
As the distance to the object decreases, to approximately 1 1/2 feet, the output acoustic frequency increases until a steady tone is generated.
As the distance to the object increases the frequency will decrease until the object is out of the monitoring range of the sensor.