Most of the time the car starts normal. Then out of the blue it fails to start. All warning lights and headlights are on , but it doesn't engage starter. Has a new battery ,terminals clean, had starter relay changed at a Chevy dealership. Day after repair did the same thing they towed to dealership . At the dealership it started everytime they tried it. Picked it up and took it home, today doing the same thing. My son went out to drive to work and nothing. I tried it 20 minute later started, tried again 20 minute later doesn't start. Thinking possible key(computer). issues tried another set same results. Just tried again nothing all lights ,warning lights, interior light, seat belt warning , everything working lit up and making noise all work but not starting. Any ideas welcomed!

 

Is the security lamp lit when you are having the problem? If it is lit, the starter won't engage.

 

Yes one of the many items appear around the dash area I did see the word security when it doesn't start. What would cause the security light to engage. Also I did have it towed back to the dealership. When it was dropped off in front of service desk it would not start, then they took it around back to parking area and dropped off. When I tried it again it did start.

 

In many cases it is caused by worn or dirty contacts on the resistor pellet in the key not making good contact with the contacts in the ignition switch, or a bad ignition switch, or intermittent wiring between the ignition switch and the security module. Try a spare or new key first, if you have one before getting too involved with other remedies. If you get a new key, the resistance value of the pellet must match that of the old key.