Parking Assistant
Parking Assistant
Parking assist (PMA)
The park assist (option 5DP with link to PDC parking assist) offers the driver a useful tool when searching for parking spaces and when parking in roadside parking slots.
Marketing calls this system Park Assist.
Park assist informs the driver whether a parking space is large enough for parking the car. Park Assist also steers the car automatically into that parking space.
The parking space can be on either driver or passenger side of the car. The driver retains control over the vehicle through use of the accelerator and brake pedal. This means that the driver, no longer involved in the complex task of steering, is able to focus full attention on the surrounding area and identify potentially dangerous situations in plenty of time.
Brief component description
The following components of the parking assist are described:
PMA control unit
The PMA control unit is secured to the rear panel in the spare wheel well. The parking assist is connected to the FlexRay bus system. The PMA control unit contains a terminal resistance for the FlexRay.
Communication with both ultrasonic sensors is performed by a LIN bus. Both ultrasonic sensors are supplied with voltage from the PMA control unit.
Ultrasonic sensors for park manoeuvering assistant
The two ultrasonic sensors on the parking assist are installed in the front side panels beside the auxiliary turn signal lights.
The function of these two ultrasonic sensors is similar to the function of the two ultrasonic sensors on Park Assist (PDC): They transmit ultrasonic impulses and receive echo impulses. The signals are evaluated by the PMA control unit. The length and depth of the parking space are then calculated from this.
The ultrasonic sensors are connected to the PMA control unit via the LIN bus.
Functional networking
The parking assist consists of the PMA control unit and 2 ultrasonic sensors which take charge of measuring out the parking space. The steering movements required for parking the car which are calculated by the control unit are then carried out by the electromechanical power steering system (EPS).
In view of the complex nature of the park assist system, many control units are interlinked by the bus system.
The parking assist can be enabled using the PDC button or by engaging reverse gear. All subsequent operation is then performed via the controller. The longitudinal guidance by the driver monitors the system using the ultrasonic sensors of the Park Assist system (PDC). The Central Information Display (CID) displays the parking operation to the driver continuously.
Park assist is not possible when towing a trailer and in sharp bends.
Refer to the Owner's Handbook for restrictions and the display concept.
System functions
Measurement of the parking space is performed automatically when driving past at speeds of up to 36 km/h. After the function has been enabled, the CID shows the driver whenever the vehicle drives past a suitable parking space. After starting the parking operation: The driver is instructed by the CID when to reverse, when to brake and when to drive forwards. The parking operation can be performed in one or more sections.
The parking operation will be interrupted in the following cases:
- Maximum parking speed of 10 km/h is exceeded
- Incorrect choice of turn flasher (for example left instead of right)
- Risk of collision with objects while parking (also on the opposite side)
- Steering action by the driver
- A door being opened
- Incorrect choice of gear
- DSC detects slip
Every one of these reasons for termination will be documented in the fault code memory of the PMA control unit with an info' entry. This is therefore not a system fault but instead an operator error by the driver. After termination, the system checks to find out if the parking operation can be resumed. If necessary, the driver can take charge of the parking operation personally.
Notes for Service department
After replacement of the PMA control unit or one of the ultrasonic sensors, no initial start-up is required. However, the control unit checks every time the engine starts if the sensor software is compatible with the control unit software. If they are not compatible, a corresponding fault code is set in the PMA control unit. In this case, the service function Updating Software for Ultrasonic Sensors needs to be run.
The PMA control unit monitors itself for faults and, if needed, makes appropriate fault code memory entries. This is not always possible in exceptional cases. This means that the control unit is not able to detect if the ultrasonic sensors (including ring seal) is correctly installed or clipped into position. Or if the side panel is damaged near the ultrasonic sensors. This can give rise to the following customer complaints without supporting fault code memory entries:
- Small parking spots are only occasionally detected
- When parking, the vehicle passes either very closely or very wide of the vehicle in front
- After the parking operation, the vehicle is either very far from, or very close to, the curb.
- The vehicle is parked at a sharp angle in the parking space.
In these cases, check to ensure that the ultrasonic sensors are correctly installed, and that the side panel near the ultrasonic sensors is undamaged (see fault patterns).
No liability can be accepted for printing or other faults. Subject to changes of a technical nature.