Parking system, function - GF54.65-P-0006CE
MODEL 204.0/2
with CODE (220) PARKTRONIC
as of Model Year 2009
/YoM 08
MODEL 204.9
with CODE (220) PARKTRONIC
as of model year 2009
MODEL 204.0/2
with CODE (230) Advanced Parking Guidance
as of model year 2012
/YoM 11 model refinement package
MODEL 204.3 with CODE (230) Advanced Parking Guidance
Function requirements, general
- Circuit 15 ON
The status of circuit 15 is sent by the electronic ignition lock control unit on model 204.3 and on model 204.0/2 as of 1.3.11 over the chassis CAN to the parking system control unit. On model 204.9 and model 204.0/2 up to 28.2.11 the electronic ignition lock control unit sends the status of circuit 15 over the body CAN to the parking system control unit.
Parking system, general
The parking system uses an ultrasonic measuring system to record the distance of the vehicle to an obstacle.
During a journey at speeds of v < 36 km/h longitudinal parking spaces on both sides of the vehicle in the direction of travel are measured and stored.
The driver is assisted when parking by means of corresponding steering and driving instructions. 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 driving backwards through narrow passages (driveway). An obstacle is in the sensing range, however the current steering wheel position means that there will be no collision.
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
- Status of backup lamp switch (transmission 711, 716) or status of gear range (transmission 722)
- Status of parking brake indicator switch
The listed input factors are determined as follows:
Direction of travel and vehicle speed:
The direction of travel and vehicle speed are calculated from the wheel speeds and the wheel rotation direction. These parameters are recorded by the following components:
- Left front axle speed sensor
- Right front axle speed sensor
- Left rear axle speed sensor
- Right rear axle speed sensor
The wheel rotation direction is only recorded by the driven wheels.
To this end the Electronic Stability Program control unit reads in the signals of the RPM sensors directly and sends them on model 204.3 and model 204.0/2 as of 1.3.11 over the chassis CAN to the parking system control unit and the instrument cluster.
On model 204.9 and model 204.0/2 up to 28.2.11 the Electronic Stability Program control unit sends the signals from the RPM sensors over the chassis CAN to the front SAM control unit and the instrument cluster.
The front SAM control unit routes this over the interior CAN to the parking system control unit.
The parking system control unit calculates the vehicle speed and its direction of travel internally.
At the same time the instrument cluster calculates the displayed speed and on model 204.3 and model 204.0/2 as of 1.3.11 it sends this over the chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the instrument cluster sends the displayed speed over the body CAN to the parking system control unit.
Status of backup lamp switch (transmission 711, 716) or status of gear range (transmission 722):
Transmission 711, 716
The direction of travel on vehicles with transmission 711 or 716 is defined through the status of the backup lamp switch.
The front SAM control unit reads in the status of the backup lamp switch directly and when the reverse gear is engaged it sends the "reverse gear engaged" signal on model 204.3 and on model 204.0/2 as of 1.3.11 over the chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the front SAM control unit sends the "reverse gear engaged" status over the body CAN to the parking system control unit.
Transmission 722:
Each gear range is engaged by the electronic transmission control control unit (transmission 722.6) or through the fully integrated transmission control unit (transmission 722.9). The electronic transmission control control unit or the fully integrated transmission control unit then sends, for example, the "gear range R engaged" status on model 204.3 and model 204.0/2 as of 1.3.11 over the drive train CAN, CDI control unit or the ME-SFI [ME] control unit and chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the CDI control unit or the ME-SFI [ME] control unit sends the status over the chassis CAN to the front SAM control unit. The front SAM control unit sends the status over the body CAN to the parking system control unit.
Status of parking brake indicator switch:
The status of the parking brake indicator switch is read in over a direct line by the front SAM control unit and on model 204.3 and model 204.0/2 as of 1.3.11 sent over chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the front SAM control unit sends the status of the parking brake indicator switch over the body CAN 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 reverse travel
- Forward travel function sequence
- Parking space recognition function sequence (with code (230) Exclusive parking assist)
- Display of potential parking spaces function sequence (with code (230) Exclusive parking assist)
- Function sequence for steering and driving instruction output (with code (230) Exclusive parking assist)
Illustration of the principle for measuring procedure
Measuring procedure function sequence
The distance measurement is based on the ultrasound measurement system. The following components are actuated by the parking system control unit:
- Outer left front parking system distance sensor
- Center left front parking system distance sensor
- Inner left front parking system distance sensor
- Inner right front parking system distance sensor
- Center right front parking system distance sensor
- Outer right front parking system distance sensor
- Outer right rear parking system distance sensor
- Inner right rear parking system distance sensor
- Inner left rear parking system distance sensor
- Outer left rear parking system distance sensor
As a result of this these emit an ultrasonic signal.
The signal reflected by an obstacle is received and evaluated. Each distance of the vehicle to an obstacle is displayed to the driver via the instrument panel parking system warning indicator and the rear parking system warning indicator.
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. Reflected 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.
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.
Monitoring ranges of distance sensors, shown on model 204.0
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.
Below a speed of v = 36 km/h the parking space detection range (D) at the right and left of the vehicle is measured up to a distance of s = 400 to 450 cm (d), and stored 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 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). The hardware of the parking system control unit is checked here for faults.
The status of the parking brake, the position of the gearshift lever (with transmission 711, 716) or the status of the gear range (with transmission 722) (reverse gear engaged or not) do not exert any influence on the parking system control unit's 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).
This is dependent on the parking brake status, the gear range status and the vehicle 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 self test all the light-emitting diodes on the parking system warning indicators are fully actuated for approx. t = 1 s.
If there are no malfunctions or errors, the two yellow horizontal "Stand by" bars illuminate on both parking system warning indicators at reduced brightness.
The background illumination of the parking system warning indicators is automatically adjusted to the ambient brightness. The parking system control unit performs 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 light-emitting diodes 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 light-emitting diodes light up on each actuated parking system warning indicator. An acoustic warning is also emitted for t = 2 s. After another t = 18 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 carriers attached on 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 malfunctions caused by the license plate carrier.
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 checking up of parking system warning 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 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" engaged (for transmission 722)
If the parking brake is on and gear range "N" is engaged, the parking system is active for t = 2 s before it is automatically switched off.
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 parking system button status is sent by the upper control panel control unit over the instrument panel LIN to the front SAM control unit. This then forwards the status on model 204.3 and model 204.0/2 as of 1.3.11 over the chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the front SAM control unit sends the parking system button status over the body CAN 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.
The intensity of the warning indicator illumination for an activated parking system changes to match the ambient brightness. To this end, the light sensor or the rain/light sensor detects the ambient brightness.
The light sensor or rain/light sensor data are read in by the front SAM control unit over the wiper/inside rearview mirror LIN and forwarded by this on model 204.3 and model 204.0/2 as of 1.3.11 over the chassis CAN to the parking system control unit.
On model 204.9 and model 204.0/2 up to 28.2.11 the front SAM control unit sends the light sensor or rain/light sensor data over the body CAN to the parking system control unit.
If the light sensor or rain/light sensor determines that it is "Night", then the parking system warning indicators are actuated at 60 % brightness.
If the light sensor or rain/light sensor determines that it is "Day", then the parking system warning indicators are actuated at 100 % brightness.
When the parking system is deactivated, only the light-emitting diode in the parking system button lights up. When driving the parking system switches between v = 60 and 16 km/h into the "Standby mode", i.e. the parking system control unit, parking system warning indicators and the distance sensors are provided with power, but the parking system warning indicators are switched to "Dark".
The respective system states are available on a transmission-specific basis in the following table:
| Status (With transmission 711, 716) | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| Parking system button | OFF | ON | ON | ON | ON | ON |
| LED in parking system button | ON | OFF | OFF | OFF | OFF | OFF |
| Gearshift lever position | X | X | X | X | All reverse gear | Reverse gear |
| v in km/h | X | ≥60 | 0 | Deceleration of > 60 down to less than 60 | ≤V U | ≤V U |
| Parking brake applied | X | X | Yes | X | no | no |
| RIZ signal (wheel pulse counter) | X | X | 0 (t ≥2 s) | X | X | X |
| Front distance sensor 1 | inactive | inactive | inactive | active for test, then inactive | active | active |
| Rear distance sensor 1 | inactive | inactive | inactive | active for test, then inactive | inactive | active |
| Instrument panel parking system warning indicator 1 | Dark 2 | OFF | dark | active for test, then dark | ON | ON |
| Rear parking system warning indicator 1 | dark | OFF | dark | active for test, then dark | dark | ON |
| Status (with transmission 722) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |||
|---|---|---|---|---|---|---|---|---|---|---|
| 4.1 | 4.2 | 4.3 | 4.4 | |||||||
| Parking system button | OFF | ON | ON | ON | ON | ON | ON | ON | ON | ON |
| LED in parking system button | ON | OFF | OFF | OFF | OFF | OFF | OFF | OFF | OFF | OFF |
| Selector lever position (gear range) | X | D, R or N | P | P | R | D | O | D, R or N | D | R or N |
| v (in km/h) | X | ≥60 | X | X | X | X | X | Deceleration of > 60 down to less than 60 | ≤V U | ≤V U |
| Parking brake applied | X | X | X | Yes | Yes | Yes | Yes | X | no | no |
| Wheel pulse counter signal | X | X | X | 0 (t ≥2 s) | 0 (t ≥2 s) | 0 (t ≥2 s) | 0 (t ≥2 s) | X | X | X |
| Front distance sensor 1 | inactive | inactive | inactive | active | inactive | active | active | active for test, then inactive | active | active |
| Rear distance sensor 1 | inactive | inactive | inactive | active | active | inactive | active | active for test, then inactive | inactive | active |
| Front parking system warning indicator on instrument panel 1 | Dark 2 | OFF | dark | dark | inactive | active | active for t = 2 s, then inactive | active for test, then dark | ON | ON |
| Rear parking system warning indicator 1 | dark | OFF | dark | dark | active | inactive | active for t = 2 s, then inactive | active for test, then dark | dark | ON |
D "Drive"
R Backward
N Neutral
P Park position
V Current speed
V U Lower speed limit (v = 16 km/h)
V 0 Upper speed limit (v = 18 km/h)
Off Supply voltage switched off
active Supply voltage applied and in operation
dark Parking system warning indicator powered, but switched to off
INACTIVE Distance sensors supplied with power but still not transmitting ultrasound
x Arbitrary condition/data
- 1 The specified operating conditions are valid only under the following conditions:
- Bus not asleep
- No malfunction of any system component
- 2 Stand by: Distance sensors and parking system warning indicators are supplied with power. The distance sensors are not transmitting an ultrasound signal and the parking system warning indicator is 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 detected
Function sequence for 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 enters measuring mode.
When obstacles are detected in front of or behind the vehicle, the driver is initially visually warned by the appropriate light-emitting diodes 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.
| Warning message (front monitoring range) | Instrument panel parking system warning indicator | Warning chime | 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 message (rear monitoring range) | Rear parking system warning indicator | Warning chime | 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 forward travel
- Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h
- Forward movement of vehicle
Forward travel function sequence
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 enters measuring mode.
When obstacles are detected in front of the vehicle the driver is initially visually warned by the lighting up of corresponding light-emitting diodes 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 the upper limit speed of v = 18 km/h is exceeded the parking assist system switches back to the standby mode.
Additional function requirements for parking space detection (with code (230) Exclusive parking assist)
- Anti-lock braking system (ABS) and Electronic Stability Program (ESP) have not intervened for t = 5 s
Parking space recognition function sequence (with code (230) Exclusive 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 activated up to v = 36 km/h.
The range of 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 (T = -40 to +85°C), air pressure, hot engine air).
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.
For a parking space to be recorded by the parking system, it must be:
- Parallel to the direction of travel
- At least b = 150 cm wide
- At least 130 cm longer than the vehicle
Provided that a parking space is detected, the parking system requires confirmation of the activation message to proceed with parking. This takes place by pressing the button O. button.
The status of the OK button is read in by the steering column tube module control unit by the die steering wheel electronics and steering LIN, which sends the status over the chassis CAN to the parking system control unit.
Parking space recognition only recognizes a free space which is geometrically suitable for parking, not whether this free space actually also represents a parking space.
Illustration of the principle of parking space detection, shown on model 204.0
Trajectory specifies the path to be taken when driving into the parking space. The trajectory consists of two arcs.
Function sequence for display of possible parking spaces (with code (230) Exclusive parking assist)
If the parking system searches for a parking space, a display is shown on the multifunction display (A1p13) of the instrument cluster in the shape of a P symbol (6). As soon as an appropriate parking space is detected by the parking system, a left directional arrow (8) or a right directional arrow (7) also appears, 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 signal to activate the display in the instrument cluster is transmitted by the parking system control unit over the chassis CAN to the instrument cluster. The switch position of the combination switch is read in by the steering column tube module and sent over the chassis CAN 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 steering and driving instruction output (with code (230) Exclusive parking assist)
- Parking space detected
- Reverse gear engaged
- Activation information confirmed
Function sequence for steering and driving instruction output (with code (230) Exclusive parking assist)
If the parking system has recorded a parking space and the parking procedure is to be conducted, corresponding steering and driving instructions are issued through the multifunction display in the instrument cluster.
The displayed arrow symbol fills or empties according to the steering angle or the distance traveled.
The steering angle is recorded by the steering wheel angle sensor.
The steering angle sensor data are read in by the steering column tube module control unit and sent to the parking system control unit over the chassis CAN.
This calculates the required steering angle from the values read in and the calculated trajectory.
The distance traveled is calculated from the RPM sensor signals. The RPM sensor signals are read in by the Electronic Stability Program control unit and transmitted to the parking system control unit over the chassis CAN.
The parking system is active during the parking procedure.
If an obstacle in the trajectory is detected during the parking procedure, the instrument cluster issues a warning message via the multifunction display and actuates the internal warning buzzer (A1h1). The warning mode is abandoned if the obstacle is removed or the obstacle position is passed.
The following displays with steering and driving instructions are available.
The drive indicator "Please drive forwards" is also possible.
In the event of "oversteer", the message "Please correct left/right" is displayed in the multifunction display. The steering wheel image remains the same, only the arrow changes direction.
The message "Parking Guidance Completed" is displayed after the target position in the parking space is reached.