How do you reset the " Theft System " on a 1999 Chevy Cavalier ?

Try this link. It's well worth the $20.00 subscription if you're going to do your own work on the car. Chilton's is the same shop manual most independent mechanics use.

Attempt to the start vehicle. The vehicle will start and then stall.

Leave the ignition on until the Theft telltale turns off in approximately 10 minutes.

Turn the ignition off.

Restart the vehicle. The vehicle will start and on this attempt. The password is now learned.

Before you do the relearn,be sure the batt is fully charged and the cables are clean and tight first, just turn the key to start position for one second and let off.ign has to be left on.light should began to flash.after ten minutes it should stop flashing. Do this three times and the relearn should be finished.If this does not work, then you will need a new passlock sensor .

it doesn't sound like the anti-theft system is the problem it sounds more like a engine grounding problem but to reset the anti-theft system you unplug the negative battery cable turn the key to the run position and reinstall the battery cable