My 2000 chevy express won't start due to security system. How do I reset it?

This is a 30 minute procedure. make sure you have a battery charger on it. to begin, insert the key into igniton, attempt to crank the engine, do not start. leave key in the on position. if the system is working properly after 10 minutes the security light should go out. turn key off for 5 seconds and then back on and attempt to crank engine again, do not start, after 10 minutes the security light should go out. repeat the above steps a third time. after the third time. turn key off and then start the van, if system is working properly it will learn the passlock again and car will start. if this does not work, try it once more making sure you followed these steps. any variation from these steps will stop the learn process. if it stiil does not work, then you either have a bad passlock module or sensor.