Blind Spot Assist, Function - GF54.71-P-0003RFM
Model 205
as of model year 2019
with code 22P (Lane tracking package)
Model 205
as of model year 2019
with code 234 (Blind Spot Monitoring)
Model 253 (except 253.99)
as of model year 2020
with code 22P (Lane tracking package)
Model 253 (except 253.99)
as of model year 2020
with code 234 (Blind Spot Monitoring)
Model 253.99
with code 22P (Lane tracking package)
Model 253.99
with code 234 (Blind Spot Monitoring)
Function requirements, general
- No undervoltage or overvoltage
- No trailer operation (with code 550 (Trailer hitch))
- Applies to all functions except exit warning:
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed: v ≥ 12 km/h (approx.)
Blind Spot Assist, general
The Blind Spot Assist monitors the rear and side areas of the vehicle using short range radar and, if necessary, informs the driver that an intentional lane change (turn signal active) is not recommended at this time. In a broader sense, the Blind Spot Assist also acts as an extension of the outside mirrors and the inside rearview mirror. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
When the vehicle is stationary, the Blind Spot Assist also monitors the rear and side areas of the vehicle using short range radar and issues exit warnings when necessary. This, too, does not release the vehicle occupants from their obligation to exit safely on their own responsibility.
The Blind Spot Assist is activated via the head unit. The following options are available for navigating in the control menu:
- Except with code 446 (Touchpad only), navigation can be performed using the Audio/COMAND control panel. The corresponding control signals are sent by the Audio/COMAND control panel (except code 446 (Touchpad only)) over the telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), navigation can be performed using the touchpad. The corresponding control signals are sent by the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) over the telematics CAN to the head unit.
- The navigation can occur with code 531 (COMAND APS) per voice control. The driver hands-free system microphone is read directly by the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The head unit finger navigation pad and the "Back" button transmit the relevant control signals via the steering wheel electronics, the steering wheel CAN, the steering column tube module control unit, the suspension FlexRay, the electronic ignition lock control unit and the user interface CAN to the head unit.
- The operating menu can be called up on the upper control panel control unit via the vehicle button. In vehicles with code 446 (Touchpad only), the upper control panel control unit sends the status of the Vehicle button to the head unit via LCP-LIN, the touchpad and the telematics CAN. In vehicles without code 446 (Touchpad only), the upper control panel control unit sends the status of the Vehicle button to the head unit via LCP-LIN, the Audio/COMAND control panel and the telematics CAN.
The head unit sends the status of the Blind Spot Assist via the user interface CAN, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
The visual warning output takes place via the following components:
- Left Blind Spot Assist readiness and warning indicator
- Right Blind Spot Assist readiness and warning indicator
The acoustic warning is output via the instrument cluster speaker; the readiness indicator is displayed in the instrument cluster.
The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Right outer rear bumper integrated radar sensor
- Left outer rear bumper integrated radar sensor
All relevant data is evaluated by the integrated rear bumper radar sensors, whereby the right rear bumper radar sensor requests the warning output.
The integrated rear bumper radar sensors operate according to the "Master-slave" principle. The master or slave function can be determined via the connector coding. The master function is defined for the integrated right rear bumper radar sensor. In other words, the integrated left rear bumper radar sensor sends its information via the periphery CAN to the integrated right rear bumper radar sensor which evaluates the corresponding information from both integrated rear bumper radar sensors and sends corresponding requests or data over the periphery CAN to the corresponding control units.
Illustration of the principle of Blind Spot Assist, shown on model 205.0
The following information is evaluated by the radar sensors integrated in rear bumper:
- Terminal status of terminal 15
- "Blind Spot Assist" status
- Engine running or drive train operational.
- Vehicle in forward movement, vehicle speed
- Steering wheel angle
- Trailer operation status (with code 550 (Trailer hitch))
Status of circuit 15:
The electronic ignition lock control unit sends the status of circuit 15 via the periphery CAN to the radar sensors integrated in the rear bumper.
"Blind Spot Assist" status:
The head unit sends the status of the Blind Spot Assist via the user interface CAN, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
Engine running or drive train operational:
In model 205, the CDI control unit or the ME-SFI [ME] control unit transmits the "engine running" or "drivetrain operational" signal via the drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit and peripherals CAN to the rear bumper integrated radar sensors.
In model 253.99, the powertrain control unit sends the "Powertrain operational" signal via the chassis FlexRay, electronic ignition lock control unit and the front end CAN to the rear bumper radar sensors.
Vehicle in forward movement, vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends this information via the suspension FlexRay, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors. The rear bumper integrated radar sensors use it to calculate the vehicle speed and the direction of travel.
Steering wheel angle:
The steering wheel angle sensor detects/records the steering wheel angle. The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information on the steering wheel angle via the suspension FlexRay, electronic ignition lock control unit and periphery CAN to the rear bumper integrated radar sensors.
Trailer recognition (with code 550 (Trailer hitch)):
When the trailer recognition control unit has detected a trailer, it sends the "Trailer detected" status to the integrated rear bumper radar sensors over the interior CAN, electronic ignition lock control unit and periphery CAN.
The Blind Spot Assist system includes the following subfunctions:
- Measuring procedure function sequence
- Function sequence for system and warning messages
- Exit warning function sequence
Measuring procedure function sequence
Objects (vehicle in blind spot) are detected using the radar measuring procedure. The radar sensors integrated in the rear bumper emit bundled electromagnetic waves as "primary signals". If these waves hit an object, they are reflected by it and are received again by the corresponding radar sensor integrated in the rear bumper as a secondary signal. These signals are used to calculate the distance and the speed of the detected object as well as its angle relative to the vehicle.
Bike riders are also detected.
Detection area of the radar sensor system, shown on model 205.0
The integrated rear bumper radar sensors detection range is based on the angles of the radar waves. These are extrapolated by the respective integrated rear bumper radar sensor to produce the actual monitoring ranges.
Function sequence for system and warning messages
When circuit 15 is switched on, the Blind Spot Assist warning indicators light up in red, until the powertrain control unit sends the "Engine running" or "Powertrain operational" signal. Additionally, when the "Assistance" menu is switched on in the instrument cluster, the readiness of the Blind Spot Assist is shown in the instrument cluster.
If system errors are detected, a corresponding message is shown in the instrument cluster.
The integrated right rear bumper radar sensor sends the function readiness status and/or the request to output fault messages over the periphery CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster (output of fault messages) and over the periphery CAN, electronic ignition lock control unit and interior CAN to the respective front door control unit, which then actuates the corresponding Blind Spot Assist readiness and warning indicator.
If a vehicle is located in the detection range of the radar sensor system, the driver is warned by the readiness and warning display for the Blind Spot Assist lighting up red in the outside mirror on the side where the vehicle is located in the blind spot. Regardless of their speed differential to the vehicle, passing vehicles are recognized and a warning is issued with Blind Spot Assist. Due to the short reaction time when the difference in speed is high, the warning message output sometimes does not have any added value. If, despite illumination of the Blind Spot Assist readiness and warning indicator, the driver still attempts to change lane and indicates this by operating the combination switch (turn signal active), a dual warning tone is additionally output via the instrument cluster speaker, which is actuated directly by the instrument cluster. The Blind Spot Assist readiness and warning indicator flashes on and off. If the vehicle leaves the radar sensor system's sensing range, the red flashing Blind Spot Assist readiness and warning indicator is switched off.
The steering column tube module control unit directly reads in the switch position of the combination switch and sends it to the integrated rear bumper radar sensors over the suspension FlexRay, electronic ignition lock control unit and periphery CAN.
Blind Spot Assist readiness and warning display, shown on left outside mirror
The following table contains the requirements for displaying system readiness and for showing the visual warning messages:
| Operating state | Blind Spot Assist readiness and warning display in the outside mirror "Off" | Blind Spot Assist readiness indicator in the instrument cluster, function status "On" | Blind Spot Assist readiness indicator in the instrument cluster, function status "Operational" | Blind Spot Assist readiness and warning display in the outside mirror lights up red | Blind Spot Assist readiness and warning display in the outside mirror flashes red |
|---|---|---|---|---|---|
| Circuit 15 OFF | X | - | - | ||
| Terminal 15 ON | - | - | - | X | |
| Engine running or drive train operational | X | - | - | ||
| Active Blind Spot Assist activated via the instrument cluster | - | X | - | ||
| Vehicle accelerates, vehicle speed v ≥ 8 km/h | X | - | X | ||
| Vehicle accelerates, vehicle speed v ≥ 25 km/h | X | X | - | ||
| Trailer recognized (with code 550 (Trailer hitch)) | X | - | - | ||
| Drive position "R" engaged | X | X | - | ||
| Vehicle recognized in blind spot | - | - | X | X | |
| Turn signal active, vehicle detected in blind spot | - | - | X | X | |
| Fault detected | X | - | - |
Gear range "R" engaged:
In model 205, drive range "R" is engaged by the fully integrated transmission control unit (transmission 722, 724, 725). The fully integrated transmission control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit over the drive train CAN, drivetrain control unit and suspension FlexRay.
In model 253.99, the powertrain control unit transmits the status "gear range R engaged" via chassis FlexRay to the electronic ignition lock control unit.
The electronic ignition lock control unit generates a "Reverse gear engaged" status and sends this over the periphery CAN to the integrated rear bumper radar sensors.
Additional function requirements for exit warning
- Blind Spot Assist is activated.
- Vehicle stationary
- The parked vehicle is not locked.
- The run-on time of 3 min after the engine is switched off (circuit 15 OFF) has not yet passed.
Before the system is switched off, the Blind Spot Assist warning displays flash 3 times.
Exit warning function sequence
The exit warning function is deactivated as soon as the vehicle comes to a standstill. The system remains operational for 3 min after the engine is switched off.
The respective Blind Spot Assist readiness and warning display lights up as soon and for as long as a vehicle is detected in the core zone of the detection range (warning level 1). If a door is opened on the corresponding side during this time, the respective Blind Spot Assist readiness and warning display flashes and a warning tone is output (warning level 2). With code 877 (Ambient lighting), the ambient lighting of the respective door is switched on and flashes red at warning level 2 in addition. Closing the respective door ends warning level 2.
The rear bumper integrated radar sensors monitor the respective detection range and communicate with each other via the peripherals CAN. The front door control units and the rear door control units transmit the door status via the interior CAN, electronic ignition lock control unit and peripherals CAN to the rear bumper integrated radar sensors.
The right rear bumper integrated radar sensor transmits the request for the output of warning messages via the peripherals CAN, electronic ignition lock control unit and interior CAN to the respective front door control unit, which then actuates the corresponding Blind Spot Assist readiness and warning display. The right rear bumper integrated radar sensor transmits the request for the output of warning tones via the peripherals CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster, which actuates the instrument cluster speaker directly. The right rear bumper integrated radar sensor transmits the request for switching on the ambient lighting in the door via the peripherals CAN, electronic ignition lock control unit and interior CAN to the ambient lighting control unit (with code 877 (Ambient lighting)).
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97FBB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998RFM |