Parking System, Function - GF54.65-P-0006RF

Model 205

up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99)

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

Courtesy of MERCEDES-BENZ USA

Function requirements in general

Terminal 15 ON

The electronic ignition lock control unit sends the status of circuit 15 to the parking system control unit over the chassis FlexRay.

Parking system, general

The parking system uses the ultrasonic measuring procedure to register 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 and stored, and the vehicle is moved in and out of a parking space semi-automatically upon the request of the driver.

Semi-automatic exiting of perpendicular parking spaces is not available.

The multifunction display in the instrument cluster and the rear parking system indicator notify the driver of the respective distance between the vehicle and the obstacle. Warning tones can also be issued through the instrument cluster speaker.

In certain situations, the parking system suppresses warnings, 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:

Direction of travel and vehicle speed
Reverse gear (transmission 716) or engaged gear range "R" (transmission 722, 724, 725)

Direction of travel and vehicle speed:

The direction of travel is defined using the wheel rotation direction. The vehicle speed is calculated from the wheel speed.

The Electronic Stability Program control unit transmits appropriate information via the chassis FlexRay to the parking system control unit and via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN 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 vehicle speed to be displayed and transmits this to the parking system control unit via the user interface CAN, the electronic ignition lock control unit and the chassis FlexRay.

Reverse gear or gear range "R" engaged:

Vehicle with transmission 716:

Vehicle with transmission 722, 724, 725:

Gear range "R" is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then transmits the "Gear range R engaged" status to the electronic ignition lock control unit via the drive train CAN, the powertrain control unit and the chassis FlexRay.

The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the type of transmission, and transmits this via the chassis FlexRay to the parking system control unit.

The parking system function 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 monitoring reverse travel
Function sequence for monitoring forward travel
Parking space recognition function sequence
Display of potential parking spaces function sequence
Function sequence for semi-automatic parking
Function sequence for semi-automatic parking space exit

Illustration of the principle for measuring procedure

Courtesy of MERCEDES-BENZ USA

Measuring procedure function sequence

The parking system is based on the ultrasonic measuring procedure. As such, the parking system control unit actuates the distance sensors directly. These then emit ultrasonic waves. 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 by means of a cross echo (see illustration of the principle of the measuring procedure). 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. With the help of the triangulation method, the distance from the vehicle to an obstacle can be calculated from two echo signals. The propagation times of the signals from the direct measurement and from the cross measurement are required for this method. A long signal propagation time therefore corresponds to a large distance, and a short signal propagation time corresponds to a short distance to the obstacle.

The parking system cannot work correctly in certain cases due to the function principle (transmitting and receiving sound waves). 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.

Courtesy of MERCEDES-BENZ USA

Shown on model 205.0

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 area at the front is a maximum of s = 100 cm.

The monitored area at the rear is a maximum of s = 120 cm.

If the distance between the vehicle and an obstacle is less than s = 20 cm (c, e), the parking system will no longer receive defined values owing to technical reasons.

At a speed of v = 36 km/h, the area to the right and left of the vehicle is measured in the horizontal depth up to a distance of s = 400 to 450 cm (parking space detection) and stored in the parking system control unit for s = 15 m.

Self-test function sequence

During the self-test the following components are checked for proper operation:

Parking system control unit
Distance sensors
Rear parking system 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.

Selecting reverse gear or gear range "R" does not have any impact 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 run when a distance sensor is "pulsed" (activated) (ultrasonic waves are transmitted).

Engaging reverse gear or gear range "R" does have an impact on the self-test of the distance sensors. If reverse gear or gear range "R" has been engaged, all distance sensors are tested. If reverse gear or gear range "R" has not been engaged, only the front distance sensors are tested.

Distance sensor test for subsequent vibrations:

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

Self-test of rear parking system indicator:

When the ignition is switched on (circuit 15 ON), the parking system control unit fully actuates all indicators in the rear parking system display for approx. t = 1 s.

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

The following states can be recorded during a self-test:

Operational problem
System error(s)

If a malfunction or system error occurs, the parking system is deactivated and the LED in the parking system button illuminates. To do this, the parking system control unit transmits the appropriate request via the chassis FlexRay, the electronic ignition lock control unit and the interior CAN to the front SAM control unit, which actuates the LED in the parking system button via the instrument panel LIN.

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 in the rear parking system indicator and/or the red warning segments in the parking system indicator in the multifunction display of the instrument cluster.

If a malfunction persists, the cause thereof is identified while driving by means of 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, depending on whether or not reverse gear or gear range "R" has been engaged, the red display elements in the rear parking system indicator or the red warning segments in the parking system indicator in the multifunction display of the instrument cluster illuminate. A warning tone is additionally emitted for t = 2 s.

In order to do this, the parking system control unit actuates the rear parking system indicator directly or transmits the request for displaying the parking system indicator in the multifunction display of the instrument cluster via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. The parking system control unit also transmits the request to output a warning to the instrument cluster via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN. The instrument cluster then actuates the external instrument cluster speaker directly. After t = 3 s, the parking system switches off, 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.

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. The national version can be coded via the diagnosis tester in order to avoid malfunctions.

Behavior in the event of overvoltage and undervoltage function sequence

The parking system behavior in the event of overvoltage or undervoltage is shown 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
Rear parking system indicator dark	Rear parking system indicator dark	No checking up of rear parking system indicators	Start pulse has no influence on parking system
No checking up if voltage is normal again	No checking up if voltage is normal again	-	No checking up of rear parking system indicators
LED in the parking system button ON	LED in the parking system button ON		-

Additional function requirements for activation and deactivation

Self-test completed successfully
Transmission not in neutral position or gear range "D" or "R" engaged

Model 205 with transmission 716 up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99) with transmission 716

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

The position of the gearshift lever (engaged gear) is recorded by the manual transmission main shifter shaft position sensor. The CDI control unit or the ME-SFI [ME] control unit reads in the signals from the manual transmission main shifter shaft position sensor directly, and transmits information about the engaged gear via the drive train CAN, the powertrain control unit and the chassis FlexRay to the parking system control unit.

Engaging the reverse gear is recorded by the manual transmission main shifter shaft position sensor. The CDI control unit or the ME-SFI [ME] control unit reads in the signal of the manual transmission main shifter shaft position sensor directly, uses it to generate the "Reverse gear engaged" signal and transmits this to the electronic ignition lock control unit via the drive train CAN, the powertrain control unit and the chassis FlexRay. The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the type of transmission, and transmits this via the chassis FlexRay to the parking system control unit.

Model 205 with transmission 722, 724, 725 up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99) with transmission 724, 725

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

The fully integrated transmission control unit transmits information about the selected gear range via the drive train CAN, the powertrain control unit and the chassis FlexRay to the parking system control unit.

The fully integrated transmission control unit sends the "Gear range R engaged" status to the electronic ignition lock control unit via the powertrain CAN, powertrain control unit and the chassis FlexRay. The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the type of transmission, and transmits this via the chassis FlexRay to the parking system control unit.

Deactivate and activate function sequence

The parking system can be deactivated and reactivated manually by pressing the parking system button in the driver side instrument panel button group. The SAM control unit reads in the status of the parking system button over the instrument panel LIN and sends this over the interior CAN, the electronic ignition lock control unit and chassis FlexRay to the parking system control unit.

If the parking system has been manually switched off using the parking system button, it is automatically switched back on again when circuit 15 is reactivated.

The brightness of the display elements in the rear parking system indicator depends on the ambient brightness. The ambient brightness is detected by the light sensor in the rain/light sensor with additional functions. The rain/light sensor with additional functions reads in the signals of the light sensor directly, evaluates them and transmits information about the ambient brightness (dimness level) via the rain/light sensor LIN to the front SAM control unit. The front SAM control unit transmits this information via the interior CAN, the electronic ignition lock control unit and the chassis FlexRay to the parking system control unit. If the light sensor detects "Night", the display elements in the rear parking system display are actuated at 60 % brightness. If the light sensor detects "Day", the display elements in the rear parking system display 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 transmits the appropriate request via the chassis FlexRay, the electronic ignition lock control unit and the interior CAN to the front SAM control unit, which actuates the LED in the parking system button via the instrument panel LIN. When driving, the parking system switches to standby mode between v = 60 and 16 km/h. In other words, the parking system control unit, the rear parking system indicator and the distance sensors are still supplied with power, but the rear parking system indicator is switched to "dark".

Warning segments (bar symbols) in the multifunction display of the instrument cluster

Courtesy of MERCEDES-BENZ USA

Additional function requirements for monitoring reverse travel

Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h (calculated from wheel speed)
Backward movement of vehicle (defined via the wheel rotation direction)
No trailer recognized (with CODE 550 (Trailer hitch))

Model 205

up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

with code 550 (Trailer coupling)

Model 253 (except 253.99)

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

with code 550 (Trailer coupling)

The trailer recognition control unit transmits the status "Trailer detected" via the interior CAN, the electronic ignition lock control unit and the chassis FlexRay to the parking system control unit.

Function sequence for monitoring reverse travel

During reverse travel the areas in front of and behind the vehicle are monitored. If 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 first warned visually by the illumination of the display elements in the rear parking system display or the warning segments in the parking system display in the multifunction display of the instrument cluster. If the distance drops below s = 30 cm, the warning is intensified first by means of an intermittent warning tone and then by a continuous warning tone. If the upper limit speed of v = 18 km/h is exceeded, the parking system changes back to standby mode. The parking system control unit actuates the rear parking system indicator directly or transmits the request for displaying the parking system indicator in the multifunction display of the instrument cluster via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. If the distance to the obstacle drops below s = 30 cm, the parking system control unit sends the request to issue a warning via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster then actuates the external instrument cluster speaker directly.

Additional function requirements for monitoring forward travel

Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h (calculated from wheel speed)

Function sequence for monitoring forward travel

When driving forwards the area in front of the vehicle is monitored. If 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 the illumination of the warning segments of the parking system indicator in the multifunction display of the instrument cluster. If the distance drops below s = 30 cm, the warning is intensified first by means of an intermittent warning tone and then by a continuous warning tone. If the upper limit speed of v = 18 km/h is exceeded, the parking system changes back to standby mode. The parking system control unit transmits the request to display the parking system indicator in the multifunction display of the instrument cluster via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. If the distance to the obstacle drops below s = 30 cm, the parking system control unit sends the request to issue a warning via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster then actuates the external instrument cluster speaker directly.

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 (calculated from the wheel speed)

The Electronic Stability Program control unit transits the status of the ABS and the ESP® via the chassis FlexRay to the parking system control unit.

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 to the left and right of the vehicle and therefore have a larger range than the other distance sensors.

In the speed range from v = 0 to 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 205.0

Courtesy of MERCEDES-BENZ USA

Depending on environmental influences (e.g. rain, snow, air humidity, extreme temperatures of e.g. T = -40 or +85°C, air pressure, hot engine air), the range of the outer front distance sensors is s = 400 to 450 cm. The data from the outer front distance sensors is 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:

Minimum vehicle width + 100cm

Maximum size of a perpendicular parking space:

Maximum vehicle width + 250cm

A boundary point is always required for parallel parking. During perpendicular parking, two boundary points are needed (on the side and rear).

After the driver has engaged the reverse gear or gear range "R", the question "Start Park Assist?" and the warning notice "Pay attention to surroundings" appears in the multifunction display of the instrument cluster. Additionally, the symbol of the OK button for "Yes" (activate) and/or the "Back" button for "No" (do not activate) is shown in the multifunction display of the instrument cluster. The driver can then start or cancel the Park Assist function using the left multifunction steering wheel button group.

The steering wheel electronics directly reads in the control signals from the left multifunction steering wheel button group and transmits this via the steering LIN to the steering column tube module. The steering column tube module control unit sends the control signals over the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster. Depending on each acknowledged message, the instrument cluster sends the status of the Park Assist to the parking system control unit via user interface CAN, electronic ignition lock control unit and chassis FlexRay.

Park Assist detects an empty space which is geometrically suitable for parking. However, it cannot detect whether the empty space is actually a parking space.

Illustration of the principle of parking space detection; shown on model 205.0

Courtesy of MERCEDES-BENZ USA

The trajectory, which consists of two arcs, forms the path to be taken into the parking space.

Parking space detection display in multifunction display of instrument cluster

Courtesy of MERCEDES-BENZ USA

Additional function requirements for display of possible parking spaces

Transmission not in neutral position or gear range "D" engaged
Vehicle speed v = 0 to 30 km/h (calculated from wheel speed)

Model 205 with transmission 716

up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99) with transmission 716

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

Model 205 with transmission 722, 724, 725

up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99) with transmission 724, 725

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

Display of potential parking spaces function sequence

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

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 parking system control unit transmits the request to activate the display in the instrument cluster via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster.

The steering column tube module control unit directly reads in the position of the combination switch and transmits it to the parking system control unit via the chassis FlexRay.

Changes to the parking situation after parking space detection are not considered by Park Assist.

Additional function requirements for semi-automatic parking

Speed v < 10 km/h (except code 498 (Japan version)) or < 7 km/h (with code 498 (Japan version)) (calculated from wheel speed)
Suitable parallel and perpendicular parking space detected

Function sequence for semi-automatic parking

If the Park Assist has detected a suitable parallel or perpendicular parking space and the parking procedure has started, various driving instructions and messages are shown to the driver in the multifunction display of the instrument cluster. The driver can now take the hands off the steering wheel. The Park Assist steers the vehicle into the parking space by means of targeted steering movements. All the driver has to do is accelerate.

The parking system control unit calculates the required steering angle from the size of the parking space and the position in relation to the space. The actual steering angle is recorded by the steering wheel angle sensor. The steering column tube module control unit reads in the data from the steering wheel angle sensor directly and transmits information about the steering angle via the chassis FlexRay to the parking system control unit. The parking system control unit sends corresponding steering commands over the chassis FlexRay to the electrical power steering control unit. The electrical power steering control unit then actuates the electric power steering actuator motor accordingly. The steering gear converts the rotation movement of the electric power steering actuator motor into a parallel movement. The parking system control unit monitors the gear rack travel of the steering gear when this takes place. This is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis FlexRay to the parking system control unit.

In order to output the driving instructions and messages, the parking system control unit transmits appropriate requests via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster.

The following driving instructions or messages can be displayed:

"Park Assist active - Please accelerate independently, pay attention to surroundings"
"Park Assist Active - Engage reverse gear" (transmission 716)
"Park Assist Active - Engage forward gear" (transmission 716)
"Park Assist Active - Please engage gear range R" (transmission 722, 724, 725)
"Park Assist Active - Please engage gear range D" (transmission 722, 724, 725)
"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))

Following a gear or gear range change, the driver must move the vehicle until it brakes automatically (maneuvering point reached).

Reverse travel or forward travel monitoring is active during parking.

The Electronic Stability Program control unit calculates the required braking torque and actuates the traction system hydraulic unit accordingly when the maneuvering points are reached. In order to do this, the parking system control unit transmits information about the remaining distance to the defined obstacle via the chassis FlexRay to the Electronic Stability Program control unit.

Changes to the remaining distance to the obstacle are also taken into consideration (e.g. a person walking into the path of the vehicle).

However, a collision cannot be prevented in all cases.

The side boundary of the parking space is defined by a recognized obstacle (e.g. a curb or bollard). If an obstacle is not detected at the side, the Park Assist aligns the vehicle flush with the front or rear obstacle. When doing this, the angled position of the vehicle in the parking space is corrected by means of appropriate maneuvering movements. The wheels are moved to the straight ahead position once the parking procedure has been completed. As soon as the vehicle is secured, the message "Park Assist complete - Please take over" appears for t = 5 s in the multifunction display of the instrument cluster. In addition, the instrument cluster actuates the external instrument cluster speaker. A warning tone sounds.

Model 205 with transmission 722, 724, 725

up to model year 2019

with code 235 (Parking Pilot with PARKTRONIC)

Model 253 (except 253.99) with transmission 724, 725

up to model year 2020

with code 235 (Parking Pilot with PARKTRONIC)

The vehicle is secured to prevent is rolling by the driver engaging gear range "P" or by the standstill control in the Electronic Stability Program control unit.

The target position of the vehicle it generally as far back and deeply into the parking space as possible.

The following situations lead to deactivation of the Park Assist:

Exceeding the permissible speed
Turning the steering wheel ("hands-on detection"):

To do this, the electrical power steering control unit reads in the signals of the electric power steering torque sensor directly, and recognizes that the steering wheel is being actively turned based on the torque difference. In this case, the electrical power steering control unit transmits an appropriate status message to the parking system control unit via the chassis FlexRay.

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

In the event of deactivation of the Park Assist due to the circumstances listed, reactivation requires a change of gear or gear range. If the vehicle is outside the previously calculated trajectory, it must be manually steered to a starting position from which a new trajectory can be calculated.

Additional function requirements for semi-automatic exit of parking space

Vehicle has been parked semi-automatically
Semi-automatic parking space exit function is activated in "Park Assist" menu of instrument cluster
Speed v < 10 km/h (except code 498 (Japan version)) or < 7 km/h (with code 498 (Japan version)) (calculated from wheel speed)

The instrument cluster transmits the status of the Park Assist to the parking system control unit via user interface CAN, electronic ignition lock control unit and chassis FlexRay.

Function sequence for semi-automatic parking space exit

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 a parking space boundary. This information is required as the 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, a rim could be damaged by the curb, for example.

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 position of the combination switch and transmits it to the parking system control unit via the chassis FlexRay. At the same time, the parking system control unit evaluates the transmission position. If reverse gear or gear range "R" has not been engaged, the parking system control unit transmits a "Start Park Assist?" prompt via the chassis FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. The symbol of the OK button for "Yes" (activate) and/or the "Back" button for "No" (do not activate) appears in the multifunction display of the instrument cluster. The driver can then start or cancel the Park Assist function using the left multifunction steering wheel button group. The steering wheel electronics directly reads in the control signals from the left multifunction steering wheel button group and transmits this via the steering LIN to the steering column tube module. The steering column tube module control unit sends the control signals over the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster. Depending on each acknowledged message, the instrument cluster sends the status of the Park Assist to the parking system control unit via user interface CAN, electronic ignition lock control unit and chassis FlexRay.

Parking space exit display in left direction of travel in the multifunction display of the instrument cluster, shown on model 205.0

Courtesy of MERCEDES-BENZ USA

In accordance with the request of the driver (left or right parking space exit), this process is visualized in the multifunction display of the instrument cluster (left parking space exit (9)).

After starting the parking space exit procedure, various driving instructions or messages are shown to the driver in the multifunction display of the instrument cluster. The driver can now take the hands off the steering wheel. The Park Assist steers the vehicle out of the parking space by means of targeted steering movements. All the driver has to do is accelerate.

The parking system control unit sends corresponding steering commands over the chassis FlexRay to the electrical power steering control unit. Then the electric power steering control unit actuates the electric power steering actuator motor correspondingly (full steering angle). The steering gear converts the rotation movement of the electric power steering actuator motor into a parallel movement. The parking system control unit monitors the gear rack travel of the steering gear when this takes place. This is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis FlexRay to the parking system control unit.

The following driving instructions or messages can be displayed:

"Park Assist active - Please accelerate independently, pay attention to surroundings"
"Park Assist Active - Engage forward gear" (transmission 716)
"Park Assist only up to 7 km/h" (with code 498 (Japan version))

Following a gear or gear range change, the driver must move the vehicle until it brakes automatically (maneuvering point reached).

Reverse travel or forward travel monitoring is active during parking space exiting.

When the Park Assist has positioned the vehicle so that the driver can drive directly out of the parking space, the parking system control unit transmits the request for output of the message "Park Assist completed - Take over vehicle" to the instrument cluster via chassis FlexRay, the electronic ignition lock control unit and user interface CAN.

The following situations lead to deactivation of the Park Assist:

Exceeding the permissible speed
Turning the steering wheel ("hands-on detection"):

Defect on an electrical component in the power steering
Defect on an electric or hydraulic component of the brake system
Faulty CAN signals
"Park Assist Active - Engage reverse gear" (transmission 716)
"Park Assist Active - Please engage gear range D" (transmission 722, 724, 725)
"Park Assist Active - Please engage gear range R" (transmission 722, 724, 725)
"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))
Driver's door and driver seat-belt buckle open at same time
Deactivation of the parking system

	Electrical function schematic of parking system		PE54.65-P-2054-97FBA
	Overview of system components of parking assistance systems		GF54.00-P-9997RF