VEHICLE transmission while in park failed to remain and moved backward on its own. My safety was at risk as a tractor trailer pulled into rest stop and had to brake b4 colliding with the said vehicle, also if anything was behind me it could have been at risk. unknown unknown NO there was NO warning lamps or messages of this problem, however there were indications on the dashboard lights that stated Blind Spot System Fault AND Cross Traffic System Fault at 45478 miles and Prior