NECK-PRO head restraints, function - GF91.16-P-0003PM

Model 203.0/ 2/ 7 

To reduce problematic neck and spine injuries caused by a rear-end collision, the driver and front passenger seats are equipped with NECK-PRO head restraints. The head restraints are activated via the NECK-PRO head restraint triggering device (N139). The front part of the head restraint is moved forward during the rear-end collision. The sensor electronics of the NECK-PRO head restraint triggering device (N139) records the vehicle acceleration and, if required, after a delay period of 20 ms also activates the driver NECK-PRO head restraint solenoid (Y24/12) and front passenger NECK-PRO head restraint solenoid (Y24/13). After at the latest 3 ms the magnetic field of these solenoids is built up and the magnetic holding force becomes less than the spring force of the springs built into the head restraints, the NECK-PRO head restraints are triggered.

The solenoids are actuated for at least 15 ms to ensure that the NECKPRO head restraints are triggered. All 3 pins of the plug connections for the NECK-PRO head restraint triggering device (N139) are permanently short-circuit protected to "circuit 30" and "circuit 31".

The NECK-PRO head restraint triggering device (N139) functions independently of the restraint systems control unit (N2/7) and cannot be diagnosed.