Brief description of components
PDC consists of the following components:
- 8 ultrasonic sensors
There are 4 ultrasonic sensors in each of the front and rear bumpers.
The ultrasonic sensors emit ultrasonic impulses. These ultrasonic impulses are reflected by obstacles (echo impulses).
The ultrasonic sensors receive and amplify these echo impulses. The amplified echo impulses are then converted into a digital signal. Each ultrasonic sensor has its own microprocessor, its own power supply and its own data connection to the PDC control unit.
IMPORTANT: Measuring range of ultrasonic sensors
The measuring range of the ultrasonic sensors is between approx. 25 centimeters and a maximum of approx. 200 centimeters. If the minimum distance that can be detected rises to an impermissible level, a fault message is entered in the fault memory.
Dirt contamination, moisture, ice and snow can cause an impermissible rise in the minimum distance that can be detected.NOTE: Cleaning the ultrasonic sensors
To make sure the system remains fully operational, keep the ultrasonic sensors clean and free from ice.
Do not clean by spraying high-pressure washers directly at the ultrasonic sensors. When cleaning, always maintain a minimum distance of at least 10 centimeters. - PDC button
The PDC button is in the center console switch cluster. The signal from the PDC button is transferred through the K-CAN to the PDC control unit.
The PDC button is used to manually switch the Park Distance Control system on and off. When the PDC is switched on, the function LED in the PDC button lights up.
If a fault develops in the PDC, the function LED in the PDC button flashes.
- PDC control unit
The PDC control unit controls the ultrasonic sensors for transmitting ultrasonic impulses. The PDC control unit also receives the digital signals from the individual ultrasonic sensors. By comparing the individual digital signals, the PDC control unit calculates the minimum distance between the ultrasonic sensor and the object.
When an object is detected, an acoustic warning and a visual warning are given.
The PDC control unit is connected to various other control units via the bus systems:
- Multi-audio system controller / Car Communication Computer
The multi-audio system controller (M-ASK) or Car Communication Computer (CCC) emits the PDC acoustic warning through the mid-range loudspeakers.
- Central Information Display
The visual PDC warnings are given in the Central Information Display (CID).
In addition, information regarding a Check-Control message that may be present is shown.
- Instrument cluster
A current Check-Control message is indicated by a symbol in the LCD display in the instrument cluster.
Moreover, the instrument cluster also provides the exterior temperature and the kilometer reading for the PDC control unit.
Ice and frost can cause an unexpected response from the ultrasonic sensors. The response characteristics of the ultrasonic sensors changes depending on the exterior temperature.
If a fault is stored in the fault memory, the kilometer reading and the exterior temperature are also stored.
- DSC control unit
The DSC control unit supplies the PDC with information about the roadspeed and distance travelled.
- Electronic transmission control
On vehicles with automatic transmission, the electronic transmission control (ESG) supplies the signal that reverse gear is engaged.
- Light module
On vehicles with manual transmission, the light module (LM) supplies the signal that reverse gear is engaged.
- Car Access System
The CAS control unit supplies the PDC with the terminal status (e.g.. terminal 15).
For vehicles from 03/2004, power is supplied to the PDC control unit through terminal 30g (active) instead of terminal 15.
- Trailer module (AHM)
The trailer module sends a signal indicating whether or not the vehicle is towing a trailer. If a trailer is recognized, the acoustic and visual warnings for the rear bumper are deactivated.