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.
Distance Control Controller Unit, Basic Function - GF30.30-P-9891A
Model all (CAR)
Location
The Active Distance Assist DISTRONIC electric controller unit is located at the center behind the radiator grille.
Task
The multi-range radar in the Active Distance Assist DISTRONIC electric controller unit detects the traffic situation in front of the vehicle.
The Active Distance Assist DISTRONIC electric controller unit processes the data of the multi-range radar for the implementation of the following functions:
- Distance control
- Collision warning
- Autonomous partial braking and maximum full-stop braking
The Active Distance Assist DISTRONIC electric controller unit is connected to the network architecture of the vehicle.
For the execution of the functions, the Active Distance Assist DISTRONIC electric controller unit processes the following information:
- Operating condition for engine/drivetrain
- Driving stage engaged
- Active transmission mode
- Parking brake status
- Vehicle speed
- Operating requests
- Brake system status
- Accelerator pedal position
- Engine drive torque
- Steering wheel angle
The Active Distance Assist DISTRONIC electric controller unit evaluates these input factors and transmits the following information and requests:
- System status
- Object information
- Requests:
- Increase/reduce engine torque
- Expand/limit drive range
- Increase/reduce the braking torque
- Brakes
- Show system and/or warning messages, output warning tones
- Status queries, diagnosis
Structure
The Active Distance Assist DISTRONIC electric controller unit contains the following component parts:
- Multi-range radar
- Controller unit
- Radome heater
The multi-range radar has the following features:
- Detection range:
- 40 m for a detection angle of 45°
- 160 m for 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 for a detection angle of 9°
- Operating frequency: 77 GHz
The multi-range radar works according to the Pulse-Doppler principle for the independent measurement of the distance and speed.
The Active Distance Assist DISTRONIC electric controller unit must be readjusted after replacement (e.g. after accident repair).
| Component descriptions | |||
| Long-range radar sensor, component description | Model 223 | GF30.30-P-3125A | |
| Model 206 | GF30.30-P-3125C | ||
| Model 297 | GF30.30-P-3125D | ||
| Model 295 | GF30.30-P-3125E |
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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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