I was driving my 96 suburban 5.7 yesterday. I went to punch it to pass a car on the highway and it flatlined. I pulled it over and tried restarting it. Would go to crank but not start. I took the keys out of the ignition and noticed the check engine, battery, and abs lights were all staying illuminated. Also my headlights weren't going off. I've never seen this before on a car ever. Anyone have any ideas on what it could be?