1997 Oldsmobile Bravada Engine cranks but wont start

1997 Oldsmobile Bravada mileage: 152,000. My car has been running perfectly, but one day my wife went out to start it and it wouldn't start. It cranks, but doesn't actually start. Also, none of the engine warning lights and gauges seem to be working, but everything else (radio, bright light indicator, hazard lights indicator) does. I've checked all the fuses and they're fine. I have even put in a new battery. Yes, there is gas in the Bravada, a half tank. My handheld diagnostic tool that hooks up to the module under the dash flashed all 8's, which means that it can't even get a reading to troubleshoot the problem. I hope it is something that can easily be fixed. What's the problem?