While driving on the interstate at 60mph, without warning the engine turned off. the dash went completely dark. no power, no steering. drifted to shoulder. put in park, turned key to off then on. vehicle started. (no warning or service codes) replicated again about 10 mins later. on city street traveling 35 mph without warning dash went dark and car shut off. same procedure to start. (no warning or service codes) unknown what caused massive failure. no indicators.