Recent years have seen steady advance in automated vehicle research and development. Similarly, communication between vehicles is not only seen as a telematics function anymore, but rather to enable better perception, higher coordination capabilities in groups of automated vehicles or even for directly plan cooperative driving maneuvers. Negotiation and planning for safety critical functions demands a high level of safety, security and robustness to external disturbances. The current state of the art in autonomous vehicles is impressive, but even after the huge amount of work that was invested in previous years, they still struggle with basic driving maneuvers such as in intersections and in lane merge scenarios. Cooperation between vehicles using wireless communication can solve these issues partially, as it improves perception, prediction and most of all planning. In this paper we present a cooperative automated lane merge function, specifically looking at challenging on-ramp merge scenarios. We detail the planning, cooperation and execution levels and show an implementation and testing approach using a 3D simulation environment. We present an evaluation of function performance and network load and discuss tradeoffs in function and network protocol design.