The Active Head Restraint system, which is integrated into the headrest unexpectedly deployed while I was safely operating the vehicle on the highway. The impact to the back of my head caused a concussion. The vehicle was not involved in a collision or other kind of accident that would trigger the system to deploy. After parking the vehicle and inspecting the headrest, it was observed that several plastic fastening components failed causing the unintended deployment of the system. It was also observed that the plastic around the metal fastening pin had failed. Internet research shows that this is a known problem with Fiat Chrysler automobiles. A Federal investigation is ongoing relating to this issue. Further, there is a class action lawsuit in the state of California.