Active Brake Assist Functions Limited : Case Study & Solution

Active Brake Assist Functions Limited Mercedes

What does active brake assist functions limited mean in Mercedes? 

The message Active Brake Assist Functions Limited in Mercedes means that the brake assist function is not working properly. This warning is typically caused by a sensor with limited visibility, which may be due to dirt or snow blocking the range of the front sensors.

In a world where technology is advancing by leaps and bounds, the active emergency brake assist system stands out as a major innovation in the field of automotive safety. This device, designed to prevent collisions by automatically activating the brakes in case of imminent danger, represents a significant step towards more autonomous and safer vehicles. Its history, marked by continuous technological advancements, reflects mankind’s relentless pursuit of mobility that is both efficient and safe.

Case Study : Active brake assist functions limited Mercedes E-Class W213

Active Brake Assist Functions Limited Mercedes E-Class
Active Brake Assist Functions Limited Mercedes E-Class

Active Brake Assist Functions Limited Mercedes how to fix ?

A Mercedes-Benz customer recently encountered a recurring issue with their Mercedes E-Class W213. Every time they started their vehicle, a message would appear on the display, stating “Active Brake Assist Functions Limited – See Owner’s Manual.” Concerned about the potential impact on their vehicle’s safety, the customer took their car to a Mercedes dealership for an inspection.

At the dealership, a qualified technician began by connecting the vehicle to the STAR Xentry diagnostic tool. This advanced system allowed the technician to retrieve all fault codes related to the Active Brake Assist Functions Limited warning. Upon analysis, the technician reassured the customer that the issue was not critical and did not compromise the basic functionality of the vehicle’s brakes. The braking system was still fully operational, but the emergency braking function was partially impaired.

To further investigate the issue, the technician used a multimeter to check the wiring of the radar sensor, which is a critical component of the Active Brake Assist system. The wiring was found to be in good condition, which prompted the technician to look closer at the radar sensor itself. It was soon discovered that the radar sensor had detached from its bracket due to a deformation on the right side of the bumper. This misalignment was causing the Active Brake Assist Functions Limited warning to trigger.

Active Brake Assist Functions Limited
Active Brake Assist Functions Limited

Remedy:

  • The radar sensor was securely fixed back into its bracket.
  • The technician then performed an on-road calibration of the autonomous braking function to ensure everything was functioning correctly.

After these interventions, the Active Brake Assist Functions Limited warning no longer appeared, and the vehicle’s emergency braking system was fully operational once again.

This case highlights the importance of addressing the Active Brake Assist Functions Limited warning promptly, as it can indicate an issue with the vehicle’s emergency braking system. While the primary braking function may still work, the reduced functionality could be a safety concern, especially in situations requiring autonomous braking assistance.

Where is the radar sensor on a Mercedes E class?

The radar sensor is typically located behind the front bumper on the right side as you see in the image below. This position allows the sensor to have an unobstructed view of the road ahead, which is crucial for its role in the Active Brake Assist system and other driver assistance features.

Active Brake Assist Functions Limited Mercedes Sensor
Active Brake Assist Functions Limited Mercedes Sensor

how to remove the Mercedes E-Class W213 radar sensor ?

Removing the radar sensor on a Mercedes E-Class W213 requires careful handling, as the sensor is a sensitive component crucial to the vehicle’s Active Brake Assist system. Here’s a general step-by-step guide on how to remove the radar sensor:

  • Remove the front bumper.
  • Remove the shock absorber from the front bumper.
  • Remove the pedestrian protection sensors along with the shock absorber from the front bumper.
  • Unlock the electrical connector and disconnect it.
  • Unscrew the screw and remove the bracket.
  • Remove the active Active Brake Assist unit from the front bumper.

How does a Mercedes emergency brake work?

At the heart of the operation of active emergency brake assist are cutting-edge technologies. Radar sensor systems, acting as the vehicle’s eyes, continuously scan the environment to detect any potential obstacles. Meanwhile, software and algorithms analyze these data in real-time and make the crucial decision to brake or not. This symbiosis between hardware and software forms the cornerstone of this revolutionary system.

Simultaneously, the Mercedes assistance system primes the emergency brake assist for imminent braking. Emergency braking is triggered as soon as the driver firmly presses the brake pedal, typically at around 4 mph (7 km/h), when approaching a vehicle or pedestrian critically. A periodic alert signal sounds, and the distance warning light on the instrument cluster flashes.

Active brake assist functions limited
Active brake assist functions limited

What are the limitations of brake assist?

Brake Assist System Limits

Despite its ingenuity, emergency braking is not infallible. Adverse weather conditions, such as heavy rain or dense fog, can hinder the performance of sensors. Current technological limitations, particularly regarding visibility and blind spots, underscore the importance of ongoing improvement and regular calibration of the system.

Can I drive with brake assist light on?

Driving with the brake assist light on is generally not recommended, as it indicates a potential issue with the vehicle’s braking system. While your car’s basic braking function may still work, the specific problem could affect features like emergency braking or collision avoidance, which are crucial for safety.

Here are some steps to take if the brake assist light comes on:

  1. Check the Owner’s Manual: Follow any guidance provided for dealing with the warning light.
  2. Drive Cautiously: If you must drive, do so with extra caution, keeping a safe distance from other vehicles and avoiding sudden maneuvers.
  3. Seek Professional Help: Have your vehicle inspected by a qualified technician as soon as possible to diagnose and address the issue.

Ignoring the warning could compromise your safety and that of others on the road, so it’s important to address the issue promptly.