Activate Brake Assist Functions Limited or active braking assistant limited function Mercedes, can appear in the car dashboardit is a failure that can affect any car of the brand Mercedes Benzequipped with brake assist, including GLA-Class, S-Class, sprinters and others. Here we let you know what it means, the origin of the failures and possible solutions.
What is Active Brake Assist Functions Limited Mercedes – Active Brake Assist Functions Limited?
Active Brake Assist or Braking Assistant is a function that can help the driver reduce the risk of collision with other vehicles, cyclists or pedestrians. In case an accident cannot be avoided, the vehicle tries to minimize the impact of the possible collision. If the Active Brake Assist Functions Limited message appears, it means that the brake assist function is not operating properly.
Active braking functions, the limited warning is, in many cases, generated by a sensor that does not have full visibility. The main cause is because the front sensors are covered with dirt or snow, making it difficult to locate them.
It can happen in some cases that the car loses power, the accelerator pedal does not respond, illuminate engine lightincluding going into emergency mode. If any of these symptoms happen to you, you should find a safe place and restart the vehicle. In case you do not have a favorable answer, proceed to clean the front grill and the upper central part of the windshield, in many cases this solution erases the messages.
If you notice the active brake assist warning message in the morning, then it is because the vehicle’s battery is running low or there are software glitches.. Depending on the Mercedes-Benz model, the warning message may indicate the following:
- Limited active brake assist functions. You should consult your owner’s manual.
- Active Brake Assist is not working properly. Seek the advice of a specialized workshop.
- Activate Brake Assist inoperative, see owner’s manual.
- Active brake assist functions are currently limited
- Active Brake Assist is not available
If the message still persists, you should read the fault codes, which you will achieve by using a scanner of complete system.
Can you drive with the Active Brake Assist light illuminated – Active Brake Assist Functions Limited?
Ultimately if you can drive, although the car will not stop in an emergency. If the fault is very serious, the vehicle may go into limp mode, which means it will only go at speeds up to 40 mph. Even the vehicle in limp mode should be driven immediately to the nearest repair shop.
Posible Problems
As we have pointed out, almost always, Active Brake Assist Functions Limited translates that the brake assist “sensor” in the front of the car is dirty, therefore it prevents determining object distances in the front. This is a common fault in Mercedes-Benz cars, especially in snowy seasons.
It is best to seek to clear the snow from the front of the car and the windshield, perhaps this will eliminate the failures of the board, you can also take the car in for an exterior wash. Other faults in Active Brake Assist Functions Limited may also be involved, such as:
- Lost Connection
- encoding problem
- low battery voltage
- damaged radar sensor
- wrong coding
The owner’s manual states that the system can be damaged by:
- Rain, snow, fog, heavy dew, if there is glare, direct sunlight, or variable ambient light.
- The sensors are dirty, cloudy, defective or covered by external agents.
- Sensors damaged by interference from other radar sources, eg. strong reflections from roadblocks in parking lots.
- When detecting a loss of pressure in the tires or a damaged tire.
- In difficult traffic situation where objects cannot be identified.
- When pedestrians or vehicles quickly enter the detection range of the sensor.
- When pedestrians are hidden by other objects
- If the outline of a pedestrian is indistinguishable from the background
- When a pedestrian is not detected by unique clothing or other objects
- In curves with a tight radius
- The pins for the accelerator pedal harness can deteriorate
- Active Brake Assist may need calibration
- Wrong windshield installed
Possible solutions
When the vehicle is still under warranty, it is best to take it to any Mercedes-Benz dealer. Now, in case the car does not have a warranty, you can proceed to:
- Remove all dirt and snow from the front windshield as well as the bumper grill.
- Deactivate transport mode, and drive the car approximately 10 kilometers (6 minutes). Then the DTC changes to passive and the sensor can be calibrated. Active Brake Assist should automatically recalibrate itself, and the fault clears on its own, if the code is due to a dirt problem.
If you notice that the fault continues then you should read the fault codes. For more information, you can check the message (yellow) in IC Active Brake Assist in the owner’s manual.
How does the active braking assistant work?
Active braking assistant limited operation Mercedes, its main purpose is to prevent accidents or reduce damage caused to pedestrians, animals, objects and other vehicles in front. Active Brake Assist applies additional brake pressure in the event the driver does not press the brake pedal hard or fast enough to avoid a collision. If the driver is unable to respond, Active Brake Assist triggers autonomous emergency braking.
Autonomous braking can be activated in emergency events if you do not react to the warning. In really critical situations, Active Brake Assist can initiate autonomous braking directly.
The Distance Warning feature alerts you when:
- From approximately four mph (7 km/h), if the car is close to a vehicle or pedestrian, it will emit an intermittent warning sound, while the distance warning light will illuminate on the dash.
- Brake immediately or take evasive action, provided it is done safely and traffic permits.
Active Brake Assist Features
- distance warning function
- Autonomous braking function
- Brake assist depending on the situation
- Vehicles with Driving Assistance Package: Evasive Steering Assist
How to deactivate active braking assistant limited operation Mercedes?
Active Brake Assist can be deactivated through the use of the steering wheel controls, applying the following:
- Find Option: Vehicle Configuration
- Scroll down to Active Brake Assists
- Select one of the settings: high, medium, low or off.
- To disable brake assist, choose the OFF option.
- You should be aware that the car will not automatically brake with brake assist disabled to avoid a collision.
Active brake assist limited function Mercedes – Active Brake Assist disabled
Active Brake Assist can cancel the brake application when any of the following conditions occur:
- Maneuvers to avoid the obstacle.
- There is no risk of collision.
- The vehicle can no longer detect an obstruction, blockage, or barrier.
Fault Codes
Among the possible fault codes that may appear are the following:
- C163691: The ‘DISTRONIC’ control unit calibration is malfunctioning. The parameter is outside the allowed range.
- C174AFB: The learned value of an operating parameter of the ‘COLLISION PREVENTION ASSIST’ control unit is out of the valid range.
- C174AFA: The learned value of an operating parameter of the ‘COLLISION PREVENTION ASSIST’ control unit is out of the valid range.
- C163691: the calibration of the ‘DISTRONIC’ control unit is malfunctioning. The parameter is outside the allowed range.
- C174AFB: The learned value of an operating parameter of the ‘COLLISION PREVENTION ASSIST’ control unit is out of the valid range.
- C174AFA: The learned value of an operating parameter of the ‘COLLISION PREVENTION ASSIST’ control unit is out of the valid range.
Troubleshooting
The error messages indicate that the driver should look for information in the owner’s manual, although the information recorded here is of little use. However, it is best to find out why the Active Brake Assist malfunction appears, so you should read the fault codes of the DISTRONIC Active Brake Assist/Active Distance Assist control module.