Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Collision Warning System Controller Unit, Detailed Information - GF30.30-P-9893-01A
Model 118, 177, 247
Overview
This document contains information on:
- General
- Function
- Radar sensor
- Controller unit
General
The Active Brake Assist controller unit (1) detects obstacles in front of the vehicle and warns the driver about possible collisions. The Active Brake Assist controller unit (1) differentiates between vehicles in front, crossing pedestrians and cyclists. If the Active Brake Assist controller unit (1) detects a collision risk, it initiates an autonomous brake application.
The Active Brake Assistant controller unit (1) includes the following component parts:
- Radar sensor
- Control unit
Function
Radar sensor
The radar sensor has the following properties:
- Detection range:
- 40 m at a detection angle of 45°
- 160 m at a detection angle of 7.5°
- Detection range (from FAP5/introduction of model series 223):
- 70 m for a detection angle of 45°
- 250 m at a detection angle of 9°
- Operating frequency: 77 GHz
The radar sensor works according to the Pulse-Doppler principle for the independent measurement of distance and speed.
Controller unit
The Active Brake Assist controller unit (1) is connected to the network architecture of the vehicle.
In order to implement the functions, the Active Brake Assist controller unit (1) processes the following information, for example:
- Terminal status of terminal 15
- Operating condition for engine/drivetrain
- Wheel speed and wheel rotation direction
- Acceleration/yaw rate
- Electronic Stability Program (ESP®) status
- Steering wheel angle and steering wheel velocity
- Accelerator pedal position
- Brake pedal position
- Driver's requests via menu settings
Depending on the national version, the Active Brake Assist controller unit (1) also processes object information from the multifunction camera behind the windshield.
The Active Brake Assist controller unit (1) processes this information and transmits the following requests, for example:
- Warning output requests
- Requirements for initiating PRE-SAFE® measures
- Increase braking torque request.
- Reduce engine torque request.
The Active Brake Assist controller unit (1) is newly adjusted after an exchange (e.g. after an accident repair) using the integrated "service adjustment mode".
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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