I have a 2015 Hyundai Santa Fe sport and I was driving on the highway and suddenly it just died out of nowhere, so I put it neutral till I could stop on the side of the freeway. And I tried and tried to start it but nothing. I still have all power to the vehicle but it won’t turn over or anything of the sort. I had power to the vehicle even when it just suddenly died. I got the car towed home and put some jumper cables on it just in case it had low voltage and still nothing it won’t even turn over but again still have power to it. When I want on the side of the road I tried to start it and I seen some smoke come from the engine bay and I couldn’t find where it was coming from. Smelled kinda like coolant but I checked that and it was all good.
Pending the information about the specifics about the car in question, the likely culprits to look at are starting and ignition circuits. Likely, combination of the two.
Starter circuit is separated into power circuit (battery to starter solenoid (B+ terminal in Hyundai parlance), solenoid engages pinion gear and sends power to the starter motor (M terminal)), and signal/control circuit (S terminal on the starter). Signal circuit on our '08 Sonata takes 12V from the battery through ignition switch, transmission switch (making sure it's in "park" or "neutral"), brake switch (making sure brakes are depressed), burglar alarm switch, to starter relay to S terminal on the solenoid.
If one is experienced, or adventurous, enough, one could put car in neutral with parking brake on, pull starter relay, and use jumper wire to bridge high current side of the relay (terminals 30 (common) and 87 (normally open)) to see if starter turns over whilst bypassing the upstream of the signal circuit.
Diagnosing starter circuit is crucial, but since the car also cut out with engine running, it points to ignition circuit which also starts at ignition switch but goes (via things like crankshaft position sensor) to ignition pack that sends high current to spark plugs. And my hunch is there is a common component (switch, sensor, relay, or fuse) that prevents both starter activation and ignition firing.