Parking system, function - GF54.65-P-0006GR
MODEL 166 up to model year 2016 with CODE 220 (PARKTRONIC)
MODEL 166 up to model year 2016 with CODE 235 (Active Park Assist)
Function requirements, general
- Terminal 15 ON
The circuit 15 status is sent by the electronic ignition lock control unit over the chassis CAN 2 to the parking system control unit.
Parking system, general
The parking system consists of PARKTRONIC (with CODE 220 (PARKTRONIC)) or Active Parking Assist (with CODE 235 (Active Parking Assist)), which assists the driver when maneuvering and parking. PARKTRONIC uses the ultrasonic measuring system to register the distance between the vehicle and an obstacle. On vehicles with CODE 235 (Active Parking Assist), while driving at speeds of v < 36 km/h, additional parallel parking spaces on both sides of the vehicle in the direction of travel are measured, stored and the vehicle is then semi-automatically parked if the driver wishes. As of 01.07.2012, this function is supplemented by the semi-automatic parking space exit function.
The Active Parking Assist system is based on the functionality of the PARKTRONIC system, but has expanded detection areas.
The distance between the vehicle and the obstacle is indicated to the driver visually and acoustically.
In certain situations warnings from the parking system are suppressed, e.g. when reversing through narrow passages (driveway). There is an obstacle within the detection range but, based on the current steering wheel position, a collision will not take place.
Parking system operation is dependent on speed and direction of travel, and therefore the following input factors have to be determined:
- Vehicle speed and direction of travel
- Status of gear range
Vehicle speed and direction of travel:
The direction of travel is defined using the wheel rotation direction. The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit directly reads in the signals from the rpm sensors and sends them over the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the parking system control unit and to the instrument cluster. The parking system control unit calculates the vehicle speed and defines the direction of travel.
At the same time the instrument cluster also calculates the speed to be displayed and sends it over the chassis CAN 2 to the parking system control unit.
Gear range status:
The fully integrated transmission control unit sends the current gear range over the drive train CAN, CDI control unit or ME-SFI [ME] control unit, chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
The parking system includes the following subfunctions:
- Measuring procedure function sequence
- Self-test function sequence
- Behavior in the event of overvoltage and undervoltage function sequence
- Activate and deactivate function sequence
- Function sequence for monitoring reverse travel
- Function sequence for monitoring forward travel
- Function sequence for parking space detection (with CODE 235 (Active Parking Assist))
- Function sequence for display of possible parking spaces on instrument cluster (with CODE 235 (Active Parking Assist))
- Function sequence for semi-automatic parking (with CODE 235 (Active Parking Assist))
- Function sequence for semi-automatic parking space exit (as of 01.07.2012 with CODE 235 (Active Parking Assist))
Illustration of the principle for measuring procedure
Measuring procedure function sequence
The parking system is based on the ultrasonic measuring procedure. In the process, the distance sensors are actuated by the parking system control unit. As a result of this these emit an ultrasonic signal. The ultrasonic waves reflected by an obstacle are received again by the distance sensors. The parking system control unit directly reads in the signals of the distance sensors and evaluates them. In principle a distinction is made between two measurements. On the one hand the direct measurement, resulting from a direct echo and on the other hand the indirect distance measurement which is achieved via a cross echo. Echoes can usually also be received from adjacent distance sensors due to the large distance sensor detection angles; these are known as cross echoes. These occur at the obstacle due to scattered reflection. The distance between the vehicle and obstacle can be calculated from two echo signals using the triangulation method. The propagation times of the signals from the direct measurement and from the cross measurement are required for this method. A long signal runtime thus equals a long distance between the vehicle and the obstacle, a short signal runtime equals a short distance between the vehicle and the obstacle.
The parking system may not work correctly in some cases because of the functional principal (sending and receiving of ultrasound waves). So for example, when approaching a strong sound absorbent obstacle (e.g. a vehicle covered in snow) it is possible that false data may be displayed.
Distance sensor monitoring ranges with CODE 220 (PARKTRONIC)
Distance sensor monitoring ranges with CODE 235 (Active Parking Assist)
The distance sensors are activated according to the direction of travel. The appropriate distance sensors are activated with forward travel for monitoring the front area (A) and the corner protection area (B).
The appropriate distance sensors are activated with reverse travel for monitoring the front area, the corner protection area and the rear area (C).
The monitored front area amounts to a maximum of s = 100 cm (c) and the monitored rear area amounts to a maximum of s = 120 cm (e). If the distance of the vehicle to an obstacle is less than s = 20 cm (a1, c1), the parking system will not obtain any more defined data for technical reasons.
For vehicles with CODE 235 (Active Parking Assist) at a speed less than v = 36 km/h, the parking space detection range (D) is scanned at the right and left of the vehicle up to a distance of s = 400 to 450 cm (d) and saved for s = 15 m in the parking system control unit.
Self-test function sequence
During the self-test the following components are checked for proper operation:
- Parking system control unit
- Distance sensors
- Front parking system warning indicator
- Rear parking system warning indicator
- Parking assist electrical lines
Parking system control unit self-test:
The parking system control unit performs a self test after the ignition is switched on (circuit 15 ON). In the process, the hardware of the parking system control unit is tested.
The gear range that is engaged does not influence the parking system control unit self-test.
Distance sensor self-test:
A self-test of the distance sensors (e.g. for connection) is only performed when a distance sensor is "pulsed" (ultrasonic transmitting).
The self-test of the distance sensors is based on the selected gear range and the speed.
Distance sensor test for subsequent vibrations:
A distance sensor test for subsequent vibrations (acoustic-physical function of distance sensor) is only conducted when the speed v = 60 km/h is exceeded or dropped below.
After the ignition is switched on (circuit 15 ON), all light-emitting diodes (LED) of the parking system warning indicators are fully actuated directly by the parking system control unit for approx. t = 1 s. If there are no malfunctions or errors, the two yellow horizontal "Standby bars" light up on both parking system warning indicators with reduced brightness.
The parking system control unit carries out further self-tests at regular intervals.
The following states can be recorded here:
- Operational problem
- System error(s)
With a malfunction or a system error, the parking system is deactivated and the display element in the parking system button in the upper control panel lights up.
Malfunction:
A malfunction can be caused by a temporary external disturbance (e.g. a jackhammer on a construction site, a steam jet or by driving through an automatic car wash). If a malfunction occurs during operation, this is indicated by the red LEDs of each actuated parking system warning indicator lighting up.
If a malfunction exists any longer, identification of the cause takes place during driving operation via a self test. If the malfunction is still present, this is interpreted as a system error.
A warning sound is not emitted.
System fault(s)
A system fault can have the following causes:
- Defective component
- Error in communication
- Overvoltage or undervoltage
If a system error is detected, the red LEDs light up on each actuated parking system warning indicator. An acoustic warning is also emitted for t = 2 s. After another t = 20 s the parking system switches off and a fault is entered into the fault memory of the parking system control unit.
The size of the license plate bracket attached to the bumper varies depending on the national version. Due to the different dimensions and shapes the parking system must be adapted to the particular circumstances. A diagnostic tester can be used to code the national version to prevent malfunction caused by the license plate bracket.
Behavior in the event of overvoltage and undervoltage function sequence
The behavior of the parking system in the event of overvoltage or undervoltage can be seen in the following table.
| On-board power supply voltage U < 9.0 V | On-board power supply voltage U > 16.0 V | Undervoltage with reset | Undervoltage without reset (start pulse) |
|---|---|---|---|
| Parking system nonfunctional | Parking system nonfunctional | The function is activated again after a reset. | Display of distance |
| Parking system warning indicators, dark | Parking system warning indicators, dark | No function test for parking system warning indicators. | Start pulse has no influence on parking system. |
| No function test, if voltage returns to normal | No function test, if voltage returns to normal | - | No function test for parking system warning indicators. |
| LED in parking system ON button | LED in parking system ON button | - | - |
Additional function requirements for activation and deactivation
- Self-test completed successfully
- Drive position "D" or "R" is engaged
If the parking brake is activated and gear range "N" is engaged, the parking system is active for t = 2 s before it is automatically switched off. The status of the parking brake is transmitted by the electric parking brake control unit via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
Activate and deactivate function sequence
The parking system can be manually deactivated or activated by pressing the parking system button in the upper control panel. The SAM control unit reads in the status of the parking system button over the battery sensor LIN and sends this via interior CAN, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
If the parking system function is manually switched off using the parking system button, then this is automatically switched on when circuit 15 is activated again.
When the parking system is on, the intensity of the illumination of warning indicators depends on the ambient brightness. The ambient brightness is sensed by the rain and light sensor. The SAM control unit reads in the status of the rain/light sensor via roof LIN and transmits this via interior CAN, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
If the rain/light sensor detects "Night", the parking system warning indicator is actuated at 60 % brightness. If the rain/light sensor detects "Day", the parking system warning indicator is actuated at 100 % brightness.
When the parking system is deactivated, only the LED in the parking system button lights up. The parking system control unit transmits the request "Activate/deactivate LED" via chassis CAN 2, electronic ignition lock control unit, interior CAN, SAM control unit and battery sensor LIN to the UCP control unit, which directly controls the LED according to the request.
When driving and between v = 60 and 16 km/h, the parking system function switches to "standby mode", i.e. the parking system control unit, parking system warning indicators and distance sensors are supplied with power, but the parking system warning indicators are switched to "dark".
Additional function requirements for monitoring reverse travel
- Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h
- Backward movement of vehicle
- No trailer recognized (with CODE 550 (Trailer hitch))
The "Trailer detected" status is transmitted by the trailer recognition control unit to the parking system control unit over the interior CAN, electronic ignition lock control unit and chassis CAN 2.
Function sequence for monitoring reverse travel
During reverse travel the areas in front of and behind the vehicle are monitored. When the lower limit speed of v = 16 km/h is dropped below, the parking system changes to measuring mode. When obstacles are detected in front of or behind the vehicle, the driver is initially visually warned by the appropriate LEDs lighting up in the parking system warning indicators. When a distance of s = 30 cm is dropped below, the warning is then intensified by an intermittent tone and subsequently by a continuous signal (see following tables). When the upper speed limit of v = 18 km/h is exceeded, the parking system goes over into stand by mode again.
The parking system control unit sends a request to issue a warning tone over chassis CAN 2 to the instrument cluster, which directly actuates the warning buzzer.
| Warning messages Front monitoring range | ||||
|---|---|---|---|---|
| Front parking system warning indicator | Warning signal | Distance (cm) | ||
| Distance sensor (B8/1, B8/6) | Distance sensor (B8/2, B8/3, B8/4, B8/5) | |||
| Visual | 1 (yellow) | - | - | < 100 |
| 2 (yellow) | - | - | < 80 | |
| 3 (yellow) | - | < 60 | < 65 | |
| 4 (yellow) | - | < 50 | < 50 | |
| 5 (yellow) | - | < 40 | < 40 | |
| Visual and acoustic | 6 (red) | Intermittent tone with f = 6 Hz | <30 | <30 |
| 7 (red) | Continuous signal | < 15 | <20 | |
| Warning messages Rear monitoring range | ||||
|---|---|---|---|---|
| Rear parking system warning indicator | Warning signal | Distance (cm) | ||
| Distance sensor (B8/7, B8/10) | Distance sensor (B8/8, B8/9) | |||
| Visual | 1 (yellow) | - | - | < 120 |
| 2 (yellow) | - | - | < 95 | |
| 3 (yellow) | - | < 80 | < 75 | |
| 4 (yellow) | - | < 55 | < 55 | |
| 5 (yellow) | - | < 40 | < 40 | |
| Visual and acoustic | 6 (red) | Intermittent tone with f = 6 Hz | <30 | <30 |
| 7 (red) | Continuous signal | <20 | <20 | |
Additional function requirements for monitoring forward travel
- Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h
- Forward movement of vehicle
Function sequence for monitoring forward travel
When driving forwards the area in front of the vehicle is monitored. When the lower limit speed of v = 16 km/h is dropped below, the parking system changes to measuring mode. When obstacles are detected in front of the vehicle the driver is initially visually warned by the lighting up of corresponding LEDs in the parking system warning indicators. When distance of s = 30 cm is dropped below, the warning is then intensified by an intermittent tone and subsequently by a continuous signal (see previous tables). When a speed of v = 18_km/h is exceeded, the parking system switches back to standby mode.
Additional function requirements for parking space detection (with CODE 235 (Active Parking Assist))
- Antilock braking system (ABS) and Electronic Stability Program (ESP®) have not intervened for t = 5 s
- Vehicle speed v < 36 km/h
Function sequence for parking space detection (with CODE 235 (Active Parking Assist))
The parking space detection function is used for simple locating of suitable parallel parking spaces. The parking space detection function is implemented via the outer front distance sensors. These monitor the area left and right of the vehicle and therefore have a larger range than the rest of the distance sensors.
At a speed of v = 0 to 18 km/h the parking system operates in mixed mode between obstacle and parking space detection. As of v ≥ 18 km/h, the parking system changes to the parking space detection function and is active until v = 36 km/h.
The range of the outer front distance sensors amounts to a maximum of between s = 400 and 450 cm depending on environmental influences (e.g. rain, snowfall, air humidity, extreme temperature, air pressure, hot engine air).
The data from the outer front distance sensors is read and evaluated by the parking system control unit.
It is calculated whether the parking space is suitable for the vehicle from the stored vehicle dimensions and deviations of the recorded parking space.
For a parking space to be recorded by the parking system, it must be:
- Parallel to the direction of travel
- At least s = 150 cm wide
- At least s = 130 cm longer than the vehicle (up to 30.06.2012)
- At least s = 100 cm longer than the vehicle (as of 01.07.2012)
The "Start Park Assist?" message appears in the instrument cluster's multifunction display. The parking system control unit transmits the request to output the message to the instrument cluster via chassis CAN 2. The instrument cluster directly actuates the multifunction display.
Alongside the warning message to pay attention to the surrounding area, the option to activate the Parking Assist system is also shown in the lower part of the multifunction display. The symbols shown in the multifunction display correspond to the OK button for "Yes" (activate) or the "Back" and voice control system OFF button for "No" (do not activate) in the left multifunction steering wheel button group.
The steering column tube module control unit reads in the control signals of the left multifunction steering wheel button group over steering LIN and steering wheel electronics and transmits them over the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
The parking system detects an empty space that is geometrically suitable for parking. However, it does not detect whether the empty space is actually suitable as a parking space.
Illustration of principle of parking space detection (with CODE 235 (Active Parking Assist))
The trajectory, which consists of two arcs, forms the path to be taken into the parking space.
Additional function requirements for display of possible parking spaces on instrument cluster (with CODE 235 (Active Parking Assist))
- Gear range "D" engaged
- Vehicle speed v = 0 to 30 km/h Function sequence for display of possible parking spaces on instrument cluster (with CODE 235 (Active Parking Assist))
While the Active Parking Assist is searching for a parking space, a P icon (6) appears in the instrument cluster multifunction display. As soon as a suitable parking space is detected by the Active Parking Assist system, a left directional arrow (7) or a right directional arrow (8) also appears alongside this icon. This arrow indicates on which side of the vehicle the parking space is located.
MODEL 166 as of 7/1/12 up to model year 2016 with CODE 235 (Active Park Assist)
The P symbol is shown in color.
Parking spaces are always looked for on both sides of the vehicle. However, only parking spaces on the passenger side are pointed out by default. To also allow parking spaces on the driver side to be displayed, the driver must actuate the turn signal in the appropriate direction. The request to activate the display in the multifunction display in the instrument cluster is sent by the parking system control unit over the chassis CAN 2 to the instrument cluster. The instrument cluster directly actuates the multifunction display.
The steering column tube module control unit reads in the switch position of the combination switch and sends this via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
Changes to the parking situation after parking space detection are not considered by the parking system.
Additional function requirements for semi-automatic parking (with CODE 235 (Active Parking Assist))
- Speed v < 10 km/h
Function sequence for semi-automatic parking (with CODE 235 (Active Parking Assist))
Insofar as the Active Parking Assist has been activated, a message appears in the multifunction display prompting the driver to operate the accelerator and brake pedals. The driver can now take his hands off the steering wheel and regulate the vehicle longitudinal control using the accelerator and brake pedal. The parking system control unit uses the size of the calculated parking space and the data from the steering wheel angle sensor to calculate the appropriate steering angle. The steering column tube module control unit directly reads in the data of the steering wheel angle sensor and sends it over chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit. The parking system control unit then sends corresponding steering commands over chassis CAN 2 to the electrical power steering control unit. The electrical power steering control unit actuates the requests to match the electric power steering actuator motor. The steering gear is used to mechanically convert the electric power steering actuator motor actuation into corresponding steering movements. Parallel to this, the multifunction display shows the "Please engage gear range D" or the "Please engage gear range R" message. After each gear range change, the driver has to control the vehicle movement until the final position is reached. At a speed of v = 7 km/h, the multifunction display shows the "Park Assist only up to 10 km/h" note.
If the vehicle (front or back) reaches a distance of s < 30 cm to the parking space boundary, the driver is notified by the first red LED in the parking system warning indicator lighting up.
Delimitation at the side of the parking space is defined by a recognized obstacle (e.g. a curb or pole). If an obstacle is not detected at the side, the vehicle is aligned flush to the front or rear obstacle.
The inclined position of the vehicle in the parking space is corrected by the parking system in a maximum of five maneuvering movements. The wheels are straightened once the parking procedure has been completed.
As soon as this end position is reached, the "Parking assistance completed - Take over vehicle" message is shown for a period of t = 5 s on the multifunction display. In addition, a warning tone is sounded. The target position of the vehicle it generally as far back and deeply into the parking space as possible.
The following situations lead to a deactivation of the system and to a termination of Active Park Assist:
- If the permissible speed of v = 10 km/h is exceeded
- Active intervention in steering wheel movement ("hands-on detection")
For this purpose, the electrical power steering control unit reads in the torque values from the electric power steering torque sensor directly and, from the difference in torque, detects whether the steering wheel is being actively turned. In this case, the electrical power steering control unit sends a corresponding status information to the parking system control unit over the chassis CAN 2.
- Defect on an electrical component in the power steering
- Faulty CAN signals
- Driver's door and driver seat-belt buckle open at same time
In the event of a deactivation of the system because of the listed circumstances, a reactivation requires a change of gear range. If the vehicle is out of the previously calculated trajectory, then the vehicle must be manually returned to the starting position, from which a new trajectory can then be calculated.
The following messages are also shown on the multifunction display:
- "Park Assist Active - Please engage gear range D"
- "Park Assist Active - Please engage gear range R"
- "Park Assist terminated - Please take over"
- "Park Assist terminated"
- "Park Assist nonfunctional"
- "Park Assist only up to 10 km/h"
Additional function requirements for semi-automatic parking space exit (as of 01.07.2012 with CODE 235 (Active Parking Assist))
- Vehicle has been parked semi-automatically
- Semi-automatic parking space exit function is activated in "Park Assist" menu of instrument cluster
- Gear range not equivalent to "P"
Function sequence for semi-automatic parking space exit (as of 01.07.2012 with CODE 235 (Active Parking Assist))
The semi-automatic parking space exit function must be preceded by semi-automatic parking of the vehicle. This ensures that the vehicle is positioned parallel to the curb, if applicable. This information is required as the Active Park Assist first requests "straight to the rear" vehicle movement to exit the parking space. If the vehicle was positioned in the parking space at an angle, the rims could be damaged by the curb. The semi-automatic parking space exit function is activated by actuating the turn signal indicator in the direction (left or right) in which the parking space is to be exited. The steering column tube module control unit directly reads in the switch position of the combination switch for this purpose and sends this via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the parking system control unit.
The parking system control unit evaluates the gear range status in parallel. If the gear range is not "P", the parking system control unit transmits the request "Start Parking Assist?" via chassis CAN 2 to the instrument cluster.
This process is visualized on the multifunction display in accordance with the driver request (exit space to left (9) or right (10)).
The driver can then activate the semiautomatic parking space exit function via the left multifunction steering wheel button group. The symbols shown in the multifunction display correspond to the OK button for "Yes" (activate) or the "Back" and voice control system OFF button for "No" (do not activate) in the left multifunction steering wheel button group.
The steering column tube module control unit reads in actuation of the left multifunction steering wheel button group over the steering LIN through the steering wheel electronics and sends the corresponding request over the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the parking system control unit. The parking system control unit then initiates the parking space exit process. The parking space exit process starts with the instruction "Engage gear range R" on the multifunction display. Once the driver has moved the vehicle back, the parking system control unit transmits the corresponding steering commands via chassis CAN 2 to the electrical power steering control unit.
The electrical power steering control unit actuates the power steering actuator motor of the power steering electromechanical controller unit in accordance with the requests (full steering lock). The steering gear is used to mechanically convert the actuator motor actuation into corresponding steering movements.
As per the required maneuvers, the parking system control unit transmits the following messages via chassis CAN 2 to the instrument cluster for visual output on the multifunction display:
- "Please engage gear range D"
- "Please engage gear range R"
If the vehicle (front or back) reaches a distance of s < 30 cm to the parking space boundary, the driver is notified by the first red LED in the parking system warning indicator lighting up.
Once the Active Parking Assist has positioned the vehicle such that the driver is able to drive straight out of the parking space, the parking system control unit sends the request to output the message "Park Assist terminated - Please take over" to the instrument cluster via chassis CAN 2.
The following circumstances will lead to a deactivation of the parking system and to a termination of the Active Park Assist:
- If the permissible speed of v = 10 km/h is exceeded
- Active intervention in steering wheel movement ("hands-on detection")
For this purpose, the electrical power steering control unit reads in the torque values from the electric power steering torque sensor directly and, from the difference in torque, detects whether the steering wheel is being actively turned.
- Defect on an electrical component in the power steering
- Faulty CAN signals
- Driver's door and driver seat-belt buckle open at same time
In the event of a deactivation of the system because of the listed circumstances, a reactivation requires a change of gear range. If the vehicle is out of the previously calculated trajectory, then the vehicle must be manually returned to the starting position, from which a new trajectory can then be calculated.
The following messages are also shown on the multifunction display:
- "Park Assist Active - Please engage gear range D"
- "Park Assist Active - Please engage gear range R"
- "Park Assist terminated - Please take over"
- "Park Assist terminated"
- "Park Assist nonfunctional"
| Electrical function schematic of parking system | PE54.65-P-2054-97NAA | ||
| Overview of system components of parking assistance systems | GF54.00-P-9997GR |