Active Brake Assist Controller Unit, Component Description - GF30.30-P-3222FG

Model 213 

up to model year 2021 

with code 258 (Collision warning system with active brake application FCW-Stop) 

Fig 1: Active Brake Assist Controller Unit Component Location - Model 213 Up To Model Year 2021 With Code 258

Courtesy of MERCEDES-BENZ USA

Location 

The Active Brake Assistant controller unit is located in the direction of travel at the rear right to the front bumper.

Task 

The Active Brake Assistant controller unit detects obstacles and vehicles moving immediately ahead and warns the driver about a possible collision.

If the Active Brake Assistant controller unit detects a risk of collision, it initiates autonomous brake application. This results in the following tasks for the Active Brake Assistant controller unit:

• Reading in input factors 
• Evaluation of input factors 
• Transmission of initial parameters 

Reading in input factors 

The Active Brake Assistant controller unit receives the following input factors via periphery CAN (CAN PER), among other things:

• Engine running or drivetrain operational
• Terminal status of terminal 15
• Wheel speed and wheel rotation direction
• Acceleration/yaw rate
• ESP® status
• Steering wheel angle and steering wheel velocity
• Accelerator pedal position
• Brake pedal position
• Switch position of combination switch (S4)
• Driver request over menu setttings in the head unit (A26/17)

Evaluation of input factors 

The input factors are evaluated by the microprocessor and the corresponding components are actuated.

Transmission of initial parameters 

The Active Brake Assistant controller unit sends the following initial parameters via periphery CAN, among other things:

• Requests to output optical and acoustic warning messages in instrument cluster
• Requirements for initiating PRE-SAFE® measures
• Request to increase the braking torque
• Request for torque reduction

Body 

The Active Brake Assistant controller unit contains the following components:

• Radar sensor
• Control unit

Properties of the radar sensor:

• Detection range of the radar sensor: s = 0 to 160 m for a detection angle of a = 45°
• 76 GHz radar sensor operating on the pulse Doppler principle for independent measurement of distance and speed

The Active Brake Assistant controller unit must be newly adjusted after exchange (e.g. after an accident repair) using the integrated "service adjustment mode".