Blind Spot Assist, Function - GF54.71-P-0003GW
Model 463
as of Model year 2013 up to Model year 2019
with code EA2 (Blind Spot Monitoring)
Function requirements, general
- No under voltage or over voltage
- "Blind Spot Assist" activated in "Assist" menu in the instrument cluster.
- Engine running or drive train operational.
- Radar sensor system not switched off.
- Vehicle moving forward.
- Vehicle speed: v ≥ 30 km/h up to maximum permissible speed
- No trailer operation (with code Q55 (Trailer hitch, ball head))
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 light active) is not recommended at this time. In a broader sense, Blind Spot Assist serves as an extension of the outside mirror. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
In the respective outside mirror, a visual indicator indicates the status of the Blind Spot Assist and warns of critical situations during a lane change (i.e. a vehicle is in the "blind spot"). The visual warning is issued via the Blind Spot Assist readiness and warning indicator in the respective outside mirror. The warning buzzer in the instrument cluster can also issue a warning tone.
The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Left rear bumper radar sensor
- Right rear bumper radar sensor
All relevant data is evaluated by the rear bumper radar sensors, whereby the right rear bumper radar sensor requests the warning output.
The 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 right rear bumper radar sensor. In other words, the left rear bumper radar sensor sends its information over chassis CAN 1 to the right rear bumper radar sensor which then evaluates the corresponding information from both rear bumper radar sensors and sends corresponding requests or data over chassis CAN 1 to the corresponding control units.
Illustration of principle shown on Model 463.23
The following information is evaluated by the Blind Spot Assist:
- Terminal status of terminal 15
- "Blind Spot Assist" status
- Engine running or drive train operational.
- Vehicle moving forward
- Vehicle speed
- Trailer recognition status (with code Q55 (Trailer hitch, ball head))
Status of circuit 15:
The electronic ignition lock control unit sends the status of circuit 15 via chassis CAN 1 to the rear bumper radar sensors.
"Blind Spot Assist" status:
The status of the Blind Spot Assist is sent by the instrument cluster via chassis CAN 2, the electronic ignition lock control unit and chassis CAN 1 to the rear bumper radar sensors.
Engine running or drive train operational:
The CDI control unit (engine 642) or ME-SFI [ME] control unit (engine 157, 273) sends the "Engine running" or "Drive train operational" signal over the chassis CAN 1 to the rear bumper radar sensors.
On engine 176, the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal over the drive train CAN, powertrain control unit and chassis CAN 1 to the rear bumper radar sensors.
Vehicle moving forward:
Forward movement is defined via the wheel rotation direction. The Electronic Stability Program control unit sends the information about the wheel rotation direction via chassis CAN 1 to the rear bumper radar sensors.
Vehicle speed:
The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit sends the information about the wheel speed via chassis CAN 1 to the rear bumper radar sensors.
Trailer recognition status (with code Q55 (Trailer hitch, ball head)): If a trailer is detected, the trailer recognition control unit sends the "Trailer detected" status via the interior CAN, the electronic ignition lock control unit and chassis CAN 1 to the rear bumper radar sensors.
The Blind Spot Assist function consists of the following sub-functions:
- Measuring procedure function sequence
- Function sequence for system and warning messages
Measuring procedure function sequence
Objects (vehicle in blind spot) are detected using the radar measuring procedure. The rear bumper radar sensors 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 rear bumper radar sensor 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.
Detection range of radar sensor system; illustration shows Model 463.23
The detection range of the rear bumper radar sensors is based on the angle of reflection of the radar waves. These are extrapolated by the respective integrated rear bumper radar sensor to produce the actual monitoring ranges.
Illustration showing actual rear monitoring range; illustration shows Model 463.23
Automatic deactivation of radar sensor system (except code ZU7 (National version for Canada) and except code ZU8 (National version for USA)):
In the vicinity of radio-astronomy stations the radar sensor system is switched off automatically due to the legal requirements on the 24-GHz-Radar system (short range radar). As a result, the Blind Spot Assist is not functional in these protected areas. The restricted areas around radio-astronomy stations are stored in each rear bumper radar sensor.
The COMAND controller unit sends the current GPS coordinates (global navigation system) over the interior CAN, electronic ignition lock control unit and the suspension CAN 1 to the rear bumper radar sensors. The rear bumper radar sensors then switch off the integrated radar sensor system in the protected areas.
With Active Blind Spot Assist, the "Radar sensor system automatically switched off, see Operator's manual" message is shown in the multifunction display of the instrument cluster. The Blind Spot Assist readiness and warning indicators light up in yellow.
The signal path for issuing warning messages is given in the function sequence "System and warning messages".
If the vehicle is parked in a restricted area, then when it is started up again the GPS coordinates are used for position finding. The driver is notified again that the radar sensor system was automatically switched off.
If the vehicle leaves the restricted area, the radar sensor system is automatically switched on again. The "Radar sensor system automatically switched off, see Operator's manual" message is canceled and the yellow lit Blind Spot Assist readiness and warning displays are switched off.
Manual switching on/off of the radar sensor system: There is also the possibility of switching the radar sensor system off and on again manually via the "Vehicle" menu in the instrument cluster.
If the radar sensor system was automatically switched off within a restricted area, the manual switch-on option is no longer available and the following message is shown "Radar sensor system automatically switched off, see operator's manual".
Function sequence for system and warning messages
When circuit 15 is switched on, the Blind Spot Assist readiness and warning indicators are switched on for t = 1.5 s turning first red then yellow. When a speed of v > 30 km/h is reached the Blind Spot Assist readiness and warning indicators are switched off and the Blind Spot Assist is ready for warning.
If a system error is detected, a corresponding message is shown in the multifunction display of the instrument cluster and the Blind Spot Assist readiness and warning indicators light up yellow.
The right rear bumper radar sensor sends the function readiness status and/or the request to output messages via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the instrument cluster (output of fault messages) and via chassis CAN 1, the electronic ignition lock control unit and interior CAN to the corresponding front door control unit, which then actuates the corresponding Blind Spot Assist readiness and warning indicator.
Blind Spot Assist readiness indicator; illustration shows left outside mirror
If, at a speed of v ≥ 30 km/h, a vehicle is located in the radar sensor system sensing range, the driver is notified of it by the Blind Spot Assist readiness and warning indicator turning read in the outside mirror on the side of the vehicle on which the vehicle is 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 the Blind Spot Assist readiness and warning lamp lighting up, the driver still attempts to change lane and indicates this by operating the combination switch (operates turn signal lights), a double-warning tone is also issued by the instrument cluster's warning buzzer. The request to issue a double warning tone is sent by the right rear bumper radar sensor via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the instrument cluster. The warning buzzer 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 signal path for issuing warning messages corresponds to that for displaying function readiness.
The steering column tube module control unit reads in the position of the combination switch directly and sends it via chassis CAN 1 to the rear bumper radar sensors.
Blind Spot Assist warning indicator, shown on left outside mirror
The requirements for displaying functional readiness and for issuing visual warning messages are given in the following table.
| Operating state | Blind Spot Assist readiness and warning indicator off | Blind Spot Assist readiness and warning indicator, yellow on | Blind Spot Assist readiness and warning indicator, red on | Blind Spot Assist readiness and warning indicator, flashing red |
|---|---|---|---|---|
| Circuit 15 OFF | X | - | - | - |
| Circuit 15 ON (t < 1.5 s) | - | - | X | - |
| Circuit 15 ON (t < 1.5 s) | - | X | - | - |
| Engine running or drive train operational | - | X | - | - |
| Vehicle accelerates, vehicle speed v ≥ 30 km/h | X | - | - | - |
| Vehicle decelerates, vehicle speed v ≤ 25 km/h | - | X | - | - |
| Trailer detected (with code Q55 (Trailer hitch, ball head)) | - | X | - | - |
| Vehicle recognized in blind spot | - | - | X | - |
| Turn signal light active, vehicle detected in blind spot | - | - | X | |
| Fault detected | - | X | - | - |
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97ZGA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GW |