Active Brake Assist doesn't seem to do anything
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 35
Likes: 13
From: San Jose, CA
2026 Mercedes GLC300, 2015 Porsche GT3
Active Brake Assist doesn't seem to do anything
I've been trying out all the features of my new GLC300. I haven't been able to get the Active Brake Assist to kick in and do anything, even when I come up on stopped traffic alarmingly fast. (And I have a decent amount of racetrack experience, so I can freak out pretty much any passenger ;-). I have the setting at "Early", so I'd expect to be triggering it. I'm not getting any warning messages about the feature being disabled. Car is a 2026 GLC300 in the US, with Driver Assistance package.
Thanks for any insights!
Thanks for any insights!
Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
First off, there are limitations of the system that are listed in the owner's manual. It only works up to a certain speed depending on the situation.
https://www.mbusa.com/en/owners/manu...e-brake-assist
Secondly, the setting does not control how soon it applies the brakes for you. It only controls how early you get the visual and acoustic warning. The braking always happens at the last possible moment. I would not recommend to try to force it. You have to cut it extremely close. One thing many don't realize with the Active Brake Assist is that it doesn't guarantee to bring the car to a full stop before colliding with an obstacle. Its main objective is to reduce the speed, so that injury and damage during a collision is minimized. If you are lucky it'll come to a full stop before colliding, but more likely you will still collide but at such reduced speed that personal injury and damage is minimized.
https://www.mbusa.com/en/owners/manu...e-brake-assist
Secondly, the setting does not control how soon it applies the brakes for you. It only controls how early you get the visual and acoustic warning. The braking always happens at the last possible moment. I would not recommend to try to force it. You have to cut it extremely close. One thing many don't realize with the Active Brake Assist is that it doesn't guarantee to bring the car to a full stop before colliding with an obstacle. Its main objective is to reduce the speed, so that injury and damage during a collision is minimized. If you are lucky it'll come to a full stop before colliding, but more likely you will still collide but at such reduced speed that personal injury and damage is minimized.
Senior Member
Joined: Dec 2024
Posts: 257
Likes: 51
From: Vancouver Island
Yes, it is not a substitute for the brake pedal. It is a safety feature.
Distronic cruise on the other hand is excellent and reliable but it brakes too late for my liking when the speed differentials are great. It's fabulous in traffic jams though.
Distronic cruise on the other hand is excellent and reliable but it brakes too late for my liking when the speed differentials are great. It's fabulous in traffic jams though.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 35
Likes: 13
From: San Jose, CA
2026 Mercedes GLC300, 2015 Porsche GT3
I guess what I'm saying is the system does absolutely nothing on my car. No warnings, no braking, no steering inputs. Has anyone else had the system intervene? In a way that prevented a potential accident? (Minimizing damage is still an accident, and completely inappropriate as a design goal)
Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
I guess what I'm saying is the system does absolutely nothing on my car. No warnings, no braking, no steering inputs. Has anyone else had the system intervene? In a way that prevented a potential accident? (Minimizing damage is still an accident, and completely inappropriate as a design goal)
Trust me, you'll experience it sooner or later. Don't take this personally, but you don't have the ***** to test it. Self-preservation will take over before you trigger it intentionally, unless you have a death wish and are willing to crash your car. If you really want to experience it, sign up for a driving event with Mercedes where they use props that look to the system like real cars and pedestrians, so you can experience it in a safe environment.
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,189
Likes: 187
From: TX
2023 GLE3502W, 2024 GLC3002W, 1967 Pontiac GTO 4 sp (sold...sniff)
We are on our 4th and 5th MB's. Automatic braking never deployed until......About 3 months ago I was crossing a main drag. There was an opening each way so I went across. Just as the nose of my car cleared the main drag, a cyclist on the sidewalk came from my right and crossed directly in front of me. The car's brakes slammed on just in time. Scared the crap out of me. Saved him and me. Whew!
Senior Member
Joined: Dec 2024
Posts: 257
Likes: 51
From: Vancouver Island
I guess what I'm saying is the system does absolutely nothing on my car. No warnings, no braking, no steering inputs. Has anyone else had the system intervene? In a way that prevented a potential accident? (Minimizing damage is still an accident, and completely inappropriate as a design goal)
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Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
Active Brake Assist cannot be turned off permanently. It reactivates automatically every time the car is started. It's a safety system at the same level as ESP and is on by default every time the car is started.
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Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
Out Of Control!!
Joined: Nov 2018
Posts: 11,403
Likes: 5,324
From: San Francisco Bay Area
2019 C63CS
I'm not sure which post you are reading. The title says Active Brake Assist and in his original post #1 he is saying he tried all the features, but he can't get Active Brake Assist to trigger. There's no mention of Driving Assistance Package in his entire first post. Anyway, let's get back on topic.
