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Discussion Starter #1
This all came about because someone on another thread asked if the A Class has seat belt pre-tensioners. Someone else suggested that they do not but as I have had them on every car I've owned since way back I found this hard to believe so I started looking, wish I hadn't though :mad:

I still haven't determined whether there are pre-tensioners or not but I have found the following:

This link https://www.mercedes-benz.co.uk/passengercars/mercedes-benz-cars/models/a-class/hatchback/explore/intelligent_drive_detail/presafe.html suggests that the A Class comes with Pre-Safe System but I can't find any other mention of it, however, the Pre-Safe System is supposed to include electric seat belt pre-tensioners

Here https://www.mercedes-benz.co.uk/passengercars/mercedes-benz-cars/models/a-class/hatchback-w177/safety/intelligent-drive.module.html it shows Presafe Sound, which I think is part of Pre-Safe system, but does not say which models it is found on and in any case this seems to be a loud sound emitted just before a collision that is presumably designed to scare the sh*** out of you, but apparently this helps

The Driver Assistance pack has PRE-SAFE PLUS (although CS told me this was part of the Parking Assist package) Pre Safe Plus: when a rear-end collision threatens, PRE-SAFE PLUS can initiate preventive measures, including warning following traffic and locking the brakes on standstill. Whether this is part of Pre-Safe system or not is unclear.

As usual CS do not know so I just wonder if anyone out there can shed any light on this subject
 

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I would think the seal belt tensioners you had on previous cars were triggered by the Air Bag system and only went off during the crash, today's version is triggered by the "Wonderful" mercedes sensors and have time to react before any physical bump.
Have a look to see if you have automatic belt adjustment, its

Multimedia system:

Settings
Vehicle
Activate or deactivate Belt adjustment.
 

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Discussion Starter #3
Multimedia system:
Settings
Vehicle
Activate or deactivate Belt adjustment.
Well this is not on my A250 Prem Plus, not even greyed out, so it must be part of another package.

Does this mean that there is no pretensioning at all or is there normal airbag type system I wonder?
 

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From my knowledge of these systems, the seat belt don't pre-tense (Don't know if that's the right word lol) when you first put them on in the A class. I know in the bigger mercedes such as a E-class they do tense up when you first put the seat belts on.

The pre-safe system i have seen for the A class is part of the 'Driving assistance pack' in the UK. And as far as i know this will tense the seat belts when the sensors detect a collision from either another car colliding into you or you colliding into someone else. As well as holding the brakes and automatically closing all windows/roof. This doesn't pre-tense the seat belts when you first put them on (I think, someone with the driving assistance pack can confirm if i'm right).

If you don't have the Driving assistance pack then you wouldn't have these Pre-Safe features.
 

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Discussion Starter #5
From my knowledge of these systems, the seat belt don't pre-tense (Don't know if that's the right word lol) when you first put them on in the A class. I know in the bigger mercedes such as a E-class they do tense up when you first put the seat belts on.

The pre-safe system i have seen for the A class is part of the 'Driving assistance pack' in the UK. And as far as i know this will tense the seat belts when the sensors detect a collision from either another car colliding into you or you colliding into someone else. As well as holding the brakes and automatically closing all windows/roof. This doesn't pre-tense the seat belts when you first put them on (I think, someone with the driving assistance pack can confirm if i'm right).

If you don't have the Driving assistance pack then you wouldn't have these Pre-Safe features.
It sounds as if there are several different sorts of seat belt pre tensioning then. The type you are describing where the seat belts tighten up when you get in the car, the Pre-Safe sort where they tension when the cars sensors see an impending collision and the old sort that have been around for years where the tensioning is tied in with the air bag system.

From the literature I have read it is suggested that Pre-Safe Sound is a standard feature, Pre-Safe System is available on the A Class but I can find no other mention of it, Pre-Safe Plus, which senses a rear collision, is part of the Driver Assistance Pack, but I don't for one minute believe that any of this is correct

MB seem very good at advertising all manor of features but less good are telling you which cars or packs contain them, even CS don't seem to know but from I have read here this is normal :rolleyes:
 
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