Q: Car won't start and security light is flashing?

The Pass-Lock security system can be effected if the battery was disconnected or dead, as well as if something like the ignition switch was replaced. Try these steps below.

The Passlock has two basic relearn procedures—a ten-minute procedure and a thirty-minute procedure. Which one you use depends on the system and what components have been replaced.

The ten-minute procedure involves trying to start the engine. If nothing happens or the engine starts and dies, the security light will be flashing. Wait ten minutes. The flashing light should go off or illuminate without flashing. When it does, turn the ignition off, wait twenty seconds, and then try to start the engine. If it starts and runs, everything is okay. If you get the same result as previously—nothing happens or the engine starts and dies with the security light flashing—wait ten more minutes.

You will now begin the thirty-minute relearn procedure, which is just the ten-minute procedure repeated three times. After turning the ignition off for the third time and waiting for twenty seconds, the engine should start and run. If it doesn’t, there may still be something wrong with the system.

After the learn procedure is completed and the engine is running, the security light may stay on steady for a few minutes and then go off—this is normal. Depending on the system, replacement of key components will necessitate that a relearn procedure be completed. These include the ignition lock cylinder, Powertrain Control Module (PCM), Body Control Module (BCM), or Instrument Panel Cluster (IPC).

If this does not work, then you may need to have the vehicle towed to the nearest Chevy dealer for further diagnosis. Be sure to have all keys for the vehicle if this has to be done.