NECK-PRO head restraint, function - GF91.16-P-0003Q: Notes

Model 209.3/ 4 

To reduce the problematic injuries to the cervical vertebrae in the event of a rear end collision, the driver and front passenger seats are fitted with NECK-PRO head restraints. The head restraints are activated via the NECK-PRO head restraint triggering device (N139). In doing so, the front part of the head restraint moves forward during a rear end collision. The electronic sensor system of the NECK-PRO head restraint triggering device (N139) senses the vehicle acceleration and engages the driver NECK-PRO head restraint solenoid (Y24/12) and the front passenger NECK-PRO head restraint solenoid (Y24/13) after a delay period of 20 ms if required. After 3 ms at the latest, the magnetic field of these solenoids is established and the retaining force of the solenoids becomes smaller than the spring force of the spring installed in the head restraints, and the NECK-PRO head restraints are triggered.

The solenoids are actuated for at least 15 ms in order to ensure that the NECK-PRO head restraints have been triggered. All 3 pins of the connector of the NECK-PRO head restraint triggering device (N139) are fused short-circuit protected to "Circuit 30" and" Circuit 31".

The NECK-PRO head restraint triggering device (N139) operates independently from the restraint systems control unit (N2/7) and does not offer any diagnostic capability.