The seat belts for the front seats are equipped with ETDs/belt buckle tensioners and seat belt force limiters. The outer seat belts in the second row of seats are equipped with ETDs and seat belt force limiters. The seat belts for the third row of seats are equipped with ETDs.

The ETDs/belt buckle tensioners tighten the seat belts in an accident, pulling them close against the body.

The ETDs/belt buckle tensioners do not correct incorrect seat positions or incorrectly fastened seat belts.

The ETDs do not pull vehicle occupants back towards the backrest.

Seat belt force limiters, when triggered, help to reduce the peak force exerted by the seat belt on the vehicle occupant.

The seat belt force limiters for the front seats are synchronized with the front air bags.

These take on a part of the deceleration force.

Thus, the force exerted on the occupant is distributed over a greater area.

The ETDs/belt buckle tensioners can only be activated when:

• the ignition is switched on.
• the restraint systems are operational; see "SRS warning lamp"
• the belt tongue is engaged in the buckle on each of the lap-shoulder belts in the front.
• the front-passenger seat is occupied and the belt tongue is engaged in the buckle on the front-passenger side.

The ETDs on the outside seats in the second row and on the seats in the third row are triggered independently of the lock status of the seat belts.

The ETDs are triggered depending on the type and severity of an accident:

• if, in the event of a head-on or rear-end collision, the vehicle decelerates or accelerates rapidly in a longitudinal direction during the initial stages of the impact
• if, in the event of a side impact, on the side opposite the impact the vehicle decelerates or accelerates rapidly in a lateral direction
• if in certain situations where the vehicle overturns and the system determines that it can provide additional protection

If the Emergency Tensioning Device/belt buckle tensioners are triggered, you will hear a bang, and a small amount of powder may also be released. Only in rare cases will the bang affect your hearing. The powder that is released generally does not constitute a health hazard. The SRS warning lamp lights up.

If the belt buckle tensioners have been triggered on the front seats, the buckle will be pulled down and will be almost flush with the upper edge of the seat. The SRS warning lamp is lit.

WARNING  
The belt buckle tensioners on the front seats only function if the belt buckles can be pulled down unobstructed. They must not be restricted in any way. Therefore, do not grab the belt buckles and do not place any objects under the belt buckles. Otherwise, the tensioning of the belt by the buckle is restricted or will not function, and will not provide any additional protection.

WARNING  
Pyrotechnical ETDs/belt buckle tensioners that were activated must be replaced.
For your safety, when disposing of the pyrotechnic ETDs/belt buckle tensioners always follow our safety instructions. These instructions are available from any authorized Mercedes-Benz Center.
The PRE-SAFE® system is equipped with electrically reversible pre-tensioners that do not need replacing after deployment.

If the front-passenger seat is not occupied, do not engage the seat belt tongue in the buckle on the frontpassenger seat. Otherwise, the Emergency Tensioning Device/belt buckle tensioner could be triggered in the event of an accident.