Brief component description
The following components are described:
- Crash-active head restraint
- ACSM or MRS: Crash safety module or multiple restraint system (ACSM stands for "Advanced Crash Safety Module", referred to as the "CRASH SAFETY MODULE ".)
- Airbag control lamp
Crash-active head restraint
The crash-active head restraint is available for the driver's and front passenger seat. From the outside the Crash-Active Head Restraint is distinguished by its two sections, which give it an easily recognized appearance. The Crash Active Head Restraint is available in two versions:
- Crash-active head restraint for the comfort seat
The depth adjustment of the head restraint can be set via the backrest upper section adjustment.
- Crash-active head restraint for all seats except comfort seat
The button for setting the head restraint (depth adjustment) is installed in the side face of the front section of the head restraint. It enables the position of the front section of the head restraint to be varied in 3 positions by up to 30 millimeters depending on what the occupant wants. For the forward depth adjustment, the front section of the head restraint only needs to be pulled (2 lock positions). For the backward depth adjustment, press the button in the front section of the head restraint. This releases the latch mechanism. The front section of the head restraint can be pressed backwards.
Spring force instantaneously propels the head restraint's front section into place in response to rear impacts. It moves forward by up to 60 millimeters, and upward up to 40 millimeters (depending upon the momentary height adjustment). This reduces the distance to the head.
| Index | Explanation |
|---|---|
| A | Crash-active head restraint (not triggered) |
| B | Crash-active head restraint (triggered) |
| 1 | Front section of the head restraint |
| 2 | Head restraint support |
| 3 | Button for setting the head restraint (depth adjustment) |
| 4 | On activation, max. total path forwards: 60 millimeters |
| 5 | On activation, max. total path upwards: 40 millimeters |
| 6 | Mechanical system for setting the head restraint as well as for motion of the head restraint in a triggering process |
When the Crash Active head restraint module or MRS control unit transmits a trigger signal, the Crash Active head restraint deploys as follows:
- The ignition squib in the pyrotechnic component ignites the propellant charge. The pyrotechnic component contains the ignition squib and propellant charge (designation in the wiring diagram: "Alternator active head restraint front left" and "Alternator active head restraint front right").
- The propellant charge drives a pin. The pin presses onto a release plate.
- When the release plate shifts, the preloaded springs are triggered. The spring force moves the front section of the head restraint forward and upward.
| Index | Explanation |
|---|---|
| 1 | Front section of the head restraint |
| 2 | Springs |
| 3 | Release plate |
| 4 | Head restraint support |
| 5 | Bracket for mounting the head restraint support |
| 6 | Holder for the pyrotechnic component |
| 7 | Pyrotechnic component (contains ignition squib and propellant charge) |
| 8 | Linkage for the head restraint adjustment |
| 9 | Button for setting the head restraint (depth adjustment) |
| 10 | Mechanical system for motion of the head restraint in a triggering process |
| 11 | Pin (Crash Active head restraint triggered) |
If SA470 "ISOFIX child-restraint mountings" or SA5DA "front passenger airbag deactivation" is installed it will be possible to deactivate the airbags and the Crash Active head restraints on the passenger side. The switch setting is selected using the integral code in the remote-control unit or the ID transmitter.
In the switch position "OFF", the following airbags on the passenger's side are not inflated:
- Front passenger airbag
- Side airbag
- Crash-active head restraint
- Knee airbag (if present)
The indicator lamp for front-passenger airbag deactivation lights up.
ACSM or MRS: Crash safety module/multiple restraint system
The crash safety module or multiple restraint system has the following tasks:
- Detecting an accident situation that is critical for the occupants
- Activating the necessary restraint systems (selectively depending on the severity of the accident and accident type)
All gas generators, pyrotechnic components and sensors are connected directly to the crash safety module or MRS control unit. The crash safety module or MRS control unit evaluates the data of the sensors. In the case of a crash, the crash safety module or MRS control unit decides whether it is necessary to trigger the seat belt tensioner and airbags and what airbags need to be deployed. The crash safety module or MRS control unit also triggers the Crash Active head restraints.
| Index | Explanation |
|---|---|
| 1 | Crash-active head restraint, front left (designation in the wiring diagram: Alternator, front left active head restraint) |
| 2 | Crash safety module (ACSM: Advanced Crash Safety Module) or MRS control unit (MRS: multiple restraint system). |
| 3 | Crash-active head restraint, front right (designation in the wiring diagram: Alternator, front right active head restraint |
Airbag control lamp
The airbag indicator light indicates the operability of the crash safety system. The airbag indicator light in the instrument panel is activated by the crash safety module or MRS control unit via the K-CAN.