Parking System, Function - GF54.65-P-0008GN

MODEL 166 as of model year 2016

with CODE 235 (Active Parking Assist with PARKTRONIC)

MODEL 292

with CODE 235 (Active Parking Assist with PARKTRONIC)

The name for "Active Parking Assist with PARKTRONIC" has been changed; as of MYJ17/2, the designation will be "Parking Pilot". The nomenclature change is not taken into account in this documentation.

Block diagram

Function requirements, general

Circuit 15 ON

The circuit 15 status is sent by the electronic ignition lock control unit via suspension CAN 2 to the parking system control unit.

Parking system, general

The parking system uses an ultrasonic measuring system to detect the distance between the vehicle and an obstacle. When driving at speeds of v < 36 km/h, parallel and perpendicular parking spaces on both sides of the vehicle in the direction of travel are measured, stored and the vehicle is moved in and out of a parking space semi-automatically upon the request of the driver.

The parking system warning displays visually inform the driver of the respective distance between the vehicle and the obstacle. Warning tones are additionally output via the warning buzzer in the instrument cluster.

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
Driving stage engaged

Vehicle speed and direction of travel:

The vehicle speed is calculated on the basis of the wheel speeds. The direction of travel is determined using the wheel rotation direction of the front wheels. The Electronic Stability Program control unit sends this information via suspension CAN 1, the electronic ignition lock control unit and suspension 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 via suspension CAN 2 to the parking system control unit.

Engaged drive position:

The fully integrated transmission control unit sends the current drive range via the drive CAN, CDI control unit or ME-SFI control unit, suspension CAN 1, electronic ignition lock control unit and suspension 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
Deactivate and activate function sequence
Function sequence for reverse travel
Forward travel function sequence
Parking space recognition function sequence
Function sequence for display of possible parking spaces on instrument cluster
Function sequence for semi-automatic parking
Function sequence for semi-automatic parking space exit

Illustration of the principle for measuring procedure

Measuring procedure function sequence

The parking system is based on the ultrasonic measuring procedure.

Here, the parking system 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 reads in the signals of the distance sensors directly 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.

Owing to its operating principle (sending and receiving sound waves), the parking system may not work properly under certain circumstances. So, for example, when approaching a highly sound-absorbent obstacle (e.g. a vehicle covered in snow), it is possible that false data may be displayed.

Shown on model 292

The distance sensors are activated according to the direction of travel.

The distance sensors responsible for monitoring the front area (A) and the front corner protection area (B) are activated when the vehicle is moving forward.

The distance sensors responsible for monitoring the rear corner protection area (C) and the rear area (D) are also activated when the vehicle is moving backward.

The monitored front area is max. s = 100 cm and the monitored rear area is max. s = 120 cm. If the distance between the vehicle and an obstacle is less than s = 20 cm (c, e), the parking system will for technical reasons no longer receive any defined data.

Below a speed of v = 36 km/h, the parking space detection range on the right and left of the vehicle is measured up to a distance of s = 400 to 450 cm 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
Parking system warning displays
Parking system electrical lines

Parking system control unit self-test:

The parking system control unit runs a self test after the ignition is switched on (circuit 15 ON). The hardware of the parking system control unit is tested here.

The selected drive range has no influence on the self-test of the parking system control unit.

Distance sensor self-test:

A self-test of the distance sensors (e. g. for connection) is only performed if a distance sensor is "pulsed" (ultrasonic waves are transmitted).

The self-test of the distance sensors depends on the engaged gear range.

Distance sensor test for subsequent vibrations:

A distance sensor test for subsequent vibrations (acoustic/physical function of the distance sensor) is performed cyclically.

Function test on parking system warning displays:

If the parking system control unit receives the "Circuit 15 ON" status, all display elements of the parking system warning displays are fully actuated for approx. t = 1 s.

If there are no malfunctions or faults, the two yellow horizontal "standby" bars light up in the parking system warning displays. The parking system control unit runs further self-tests at regular intervals.

The following states can be recorded here:

Operational problem
System error(s)

If there is a malfunction or system error, the parking system is deactivated and the LED in the parking system button 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 illumination of the red display elements of the currently actuated parking system warning display. These are directly actuated by the parking system control unit for t = 5 s.

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 error:

A system error can have the following causes:

Defective component
Error in communication
Overvoltage or undervoltage

If a system error is detected, the red display elements of the rear parking system warning display or those of the front parking system warning display light up, depending on the engaged drive range. A warning tone is also output for t = 2 s.

For this purpose, the parking system control unit sends a corresponding request via suspension CAN 2 to the instrument cluster. The instrument cluster then actuates the warning buzzer directly to issue the acoustic warning. The parking system switches off after an additional t = 3 s. A fault is entered in the fault memory of the parking system control unit, and the LED in the parking system button lights up.

If the system error occurs again after a driving cycle, the described scenario is repeated.

Behavior in the event of overvoltage and undervoltage function sequence

The behavior of the parking system in the event of overvoltage or undervoltage is shown in the following table.

On-board electrical system voltage U < 9.0 V	On-board electrical system 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 displays dark	Parking system warning displays dark	No function test on parking system warning displays	Start pulse has no influence on the parking system
No function test, if voltage returns to normal	No function test, if voltage returns to normal	-	No function test on parking system warning displays
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

Deactivate and activate function sequence

The parking system can be manually deactivated or activated by pressing the parking system button in the upper control panel control unit.

The SAM control unit reads in the status of the parking system button via battery sensor LIN and sends this via the interior CAN, electronic ignition lock control unit and suspension CAN 2 to the parking system control unit.

If the parking system function is manually switched off using the parking system button, the function is automatically switched on again when circuit 15 is activated again.

The intensity of the parking system warning display illumination for an activated parking system changes depending on the ambient brightness.

The ambient brightness is sensed by the rain/light sensor with additional functions. The SAM control unit reads in the data from the rain/light sensor with additional functions via the roof LIN and sends this data via the interior CAN, electronic ignition lock control unit and suspension CAN 2 to the parking system control unit. If the rain and light sensor with additional functions detects "Night", the parking system warning displays are actuated at 60 % brightness. If the rain and light sensor with additional functions detects "Day", the parking system warning displays are 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 sends a corresponding request via suspension CAN 2, the electronic ignition lock control unit, interior CAN, SAM control unit and battery sensor LIN to the upper control panel control unit. When driving, the parking system switches to standby mode at speeds between v = 60 and 16 km/h. In other words, the parking system control unit, the parking system warning displays and the distance sensors are still supplied with power but the parking system warning displays are switched to "dark".

Additional function requirements for 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))

Model 166

as of model year 2016

with code 235 (Active Parking Assist with PARKTRONIC)

with code 550 (Trailer coupling)

Model 292

with code 235 (Active Parking Assist with PARKTRONIC)

with code 550 (Trailer coupling)

The "Trailer detected" status is sent by the trailer recognition control unit to the parking system control unit via the interior CAN, electronic ignition lock control unit and suspension CAN 2.

Function sequence for reverse travel

During reverse travel the areas in front of and behind the vehicle are monitored. When the speed drops below the lower limit speed of v = 16 km/h, 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 illumination of the appropriate warning segments of the parking system warning display.

When the distance drops below s = 30 cm, the warning is intensified first means of an intermittent tone and then by means of a continuous tone. When the speed exceeds the upper speed limit of v = 18 km/h, the parking system changes back to standby mode.

If drive range "R" is engaged immediately after the engine is started, no warning tone is issued even if an obstacle is located immediately in front of the vehicle (only a visual warning is given).

Additional function requirements for forward travel

Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h

Forward travel function sequence

When driving forwards the area in front of the vehicle is monitored. When the speed drops below the lower limit speed of v = 16 km/h, the parking system changes to measuring mode. When obstacles are detected in front of the vehicle, the driver is first warned visually by illumination of the appropriate warning segments in the parking system warning display.

Additional function requirements, parking space recognition

Ant-lock braking system (ABS) and Electronic Stability Program (ESP®) have not intervened for t = 5 s
Vehicle speed v < 36 km/h

Parking space recognition function sequence

The parking space detection function is used for simple locating of suitable parallel or perpendicular 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.

In a vehicle speed range of v = 0 tos 18 km/h, the parking system operates in mixed mode between obstacle and parking space detection. From v > 18 km/h, the parking system changes to the parking space detection function and is active up to v = 36 km/h.

Shown on model 292

Depending on environmental influences (e. g. rain, snowfall, air humidity, extreme temperatures of, for example, T = -40 or +85 °C, air pressure, hot engine air), the max. range of the outer front distance sensors lies between s = 400 and 450 cm.

The data from the front outer distance sensors are read in 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.

Minimum size of a parallel parking space (parallel to the direction of travel):

At least s = 150 cm wide
At least s = 100 cm longer than the vehicle.

Minimum size of a perpendicular parking space:

A minimum vehicle width of +s = 100 cm
A maximum vehicle width of +s = 250 cm

A boundary point is always required for longitudinal and transverse parking.

After the driver has engaged gear range "R", the "Activate Park Assist?"

query appears in the multifunction display of the instrument cluster. Alongside the warning message to pay attention to the surrounding area, the option to activate the Active Parking Assist is also shown in the lower part of the multifunction display. The semi-automatic parking space entry function is activated using the OK button. The procedure is aborted by pressing the "Back" button. The buttons are in the left multifunction steering wheel button group.

The steering wheel electronics read in the signals from the multifunction steering wheel button group directly and send these signals via the steering LIN, steering column tube module control unit, suspension CAN 1, electronic ignition lock control unit and suspension CAN 2 to the parking system control unit.

The parking system detects an empty space which is geometrically suitable for parking. It does not recognize whether the empty space is actually suitable as a parking space.

Parking space detection, illustration of the principle

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

Gear range "D" engaged
Vehicle speed v = 0 to 30 km/h

Function sequence for display of possible parking spaces on instrument cluster

When the parking system is searching for a parking space, a P symbol (6) appears in the multifunction display of the instrument cluster. As soon as an appropriate parking space is detected by the parking system, a left directional arrow (7) or a right directional arrow (8) indicating the side of the vehicle on which the parking space is located, appears in addition to the symbol.

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 signal to activate the display in the multifunction display is sent by the parking system control unit via suspension CAN 2 to the instrument cluster.

The position of the combination switch is read in by the steering column tube module control unit and sent via suspension CAN 1, the electronic ignition lock control unit and suspension CAN 2 to the parking system control unit.

Changes to the parking situation after parking space detection are not taken into account by the parking system.

Additional function requirement for semi-automatic parking

Speed v < 10 km/h (except code 498 (Japan version))
Speed v < 7 km/h (with code 498 (Japan version))

Function sequence for semi-automatic parking

If the Active Parking Assist has been activated, appropriate driving instructions appear on the multifunction display in the instrument cluster. The driver can now take the hands off the steering wheel.

The parking system control unit calculates the corresponding steering movement based on the size of the detected parking space as well as the data from the steering wheel angle sensor. The steering column tube module control unit reads in the data of the steering wheel angle sensor directly and sends it via suspension CAN 1, the electronic ignition lock control unit and suspension CAN 2 to the parking system control unit. The parking system control unit then sends corresponding steering commands via suspension CAN 2 to the electrical power steering control unit. The electrical power steering control unit actuates the electric power steering actuator motor correspondingly. The steering gear is used to mechanically convert the electric power steering actuator motor actuation into steering movements.

At the same time, the request to engage the required gear range is shown in the multifunction display.

Here, the parking system control unit monitors the toothed rack travel of the steering gear. For this purpose, the electrical power steering control unit then sends the corresponding information via suspension CAN 2 to the parking system control unit.

After the respective gear range or gear has been changed, the driver must move the vehicle until the end position has been reached and the vehicle brakes automatically.

From a speed of v = 7 km/h, the message "Park Assist only up to 10 km/h" is displayed in the multifunction display (except code 498 (Japan version))
From a speed of v = 5 km/h, the message "Park Assist only up to 7 km/h" is displayed in the multifunction display (with code 498 (Japan version))

If the vehicle reaches (forward or backward) a distance of s < 30 cm to the parking space boundary, this is signaled to the driver by illumination of the first red display element in the corresponding parking system warning display.

At the same time, the parking system control unit sends information about the current remaining distance to the obstacle via suspension CAN 2, the electronic ignition lock control unit and suspension CAN 1 to the Electronic Stability Program control unit.

The Electronic Stability Program control unit calculates the required braking torque and actuates the traction system hydraulic unit directly. The vehicle is braked. The vehicle is braked to stop at the required maneuvering points as well as an in the target parking position.

Any changes that occur suddenly in the remaining distance to the obstacle are also taken into account (e. g. a person walks into the path of the vehicle). Depending on the current driving situation, however, it is not always possible to prevent a collision in such cases.

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 by means of corresponding maneuvering movements. The wheels are straightened once the parking procedure has been completed. Once the vehicle is secured, the message "Park Assist complete - Take over vehicle" appears for a period of t = 5 s in the multifunction display of the instrument cluster.

The vehicle is secured by the driver engaging the gear range "P" or operating the parking brake.

Additionally, the warning buzzer issues a warning tone.

The target position of the vehicle is generally as far into the parking space as possible.

The following situations lead to deactivation of the parking system and therefore to cancellation of the Active Parking Assist:

Exceedance of the permissible speed of v = 10 km/h (except code 498 (Japan version)) or v = 7 km/h (with code 498 (Japan version))
Turning the steering wheel ("hands-on detection").

To do this, the electrical power steering control unit directly reads in the torque values of the electric power steering torque sensor and recognizes that the steering wheel is actively turned based on the torque difference. In this case, the electrical power steering control unit sends corresponding status information to the parking system control unit via suspension CAN 2.

Defect on an electrical component in the power steering
Defect on an electric or hydraulic component of the brake system
Faulty CAN signals
Driver's door and driver seat-belt buckle open at same time
Deactivation of the parking system by pressing the parking system button

In the event of deactivation of the parking system due to the listed circumstances, reactivation is only possible after the drive range has been changed. 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 additionally shown on the multifunction display in the instrument cluster:

"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" (except code 498 (Japan version))
"Park Assist only up to 7 km/h" (with code 498 (Japan version))

Additional function requirements for semi-automatic exit of parking space

Vehicle has been parked semi-automatically
Semi-automatic parking space exit function activated in "Park Assist" menu
Gear range not equivalent to "P"
Obstacle detected in front of and behind vehicle
Turn signal indicator set (in exit parking space direction)

Function sequence for semi-automatic parking space exit

The semi-automatic parking space exit function must be preceded by the semi-automatic parking space entry function and can only be executed on the side of the road on which the vehicle was parked. This ensures that the vehicle is positioned parallel to the curb, if applicable. This information is required as the Active Parking 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 reads in the position of the combination switch directly and sends it via suspension CAN 1, the electronic ignition lock control unit and suspension CAN 2 to the parking system control unit.

As the same time, the parking system control unit evaluates the drive range status. If the drive range is not "P", the parking system control unit sends the request "Start Parking Assist?" via suspension CAN 2 to the instrument cluster.

The driver can then activate the semiautomatic parking space exit function using the left multifunction steering wheel button group corresponding to the driver request (exit parking space at left or right). The semiautomatic parking space exit function is activated via the OK button. The procedure is aborted by pressing the "Back" button.

The parking system control unit sends corresponding steering commands to the electrical power steering control unit via suspension CAN 2.

The electrical power steering control unit actuates the electric power steering actuator motor correspondingly (full steering angle). The steering gear is used to mechanically convert the electric power steering actuator motor actuation into corresponding steering movements.

According to the necessary maneuvering movements, the parking system control unit sends the request for visual output of the corresponding driving instructions via suspension CAN 2 to the instrument cluster.

If the vehicle reaches (forward or backward) a distance of s < 30 cm to the parking space boundary (maneuvering point), this is signaled to the driver by illumination of the first red display element in the corresponding parking system warning display.

The vehicle is braked automatically at the corresponding maneuvering points.

The Electronic Stability Program control unit calculates the required braking torque and actuates the traction system hydraulic unit directly.

The vehicle is braked.

Once the Active Parking Assist has positioned the vehicle so that the driver can drive directly out of the parking space, the parking system control unit sends the message "Parking assistance completed - Take over vehicle" via suspension CAN 2 to the instrument cluster.

The following situations lead to deactivation of the parking system and therefore to cancellation of the Active Parking Assist:

Exceedance of permissible speed of v = 10 km/h (except code 498 (Japan version)) or of v = 7 km/h (with code 498 (Japan version))
Turning the steering wheel ("hands-on detection").
To do this, the electrical power steering control unit directly reads in the torque values of the electric power steering torque sensor and recognizes that the steering wheel is actively turned based on the torque difference. In this case, the electrical power steering control unit sends corresponding status information to the parking system control unit via suspension CAN 2.
Defect on an electrical component in the power steering
Defect on an electric or hydraulic component of the brake system
Faulty CAN signals
Driver's door and driver seat-belt buckle open at same time
Deactivation of the parking system by pressing the parking system button

The following messages are also displayed on the instrument cluster:

"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-2055-97NBA
	Overview of system components of parking assistance systems		GF54.00-P-9997GN