The Passlock system should normally never need attention. If on a rare occasion you are having issues with it here are some suggested actions to correct the problem.
There are electronic sensors within the lock cylinder housing that are programmed to see certain things within the cylinder when the key is inserted. There is no sensor on or in the key, but sensors in the housing.
The key housing sensors and the Body Control Module work together to establish the Passlock system. The ignition switch has nothing to do with the Passlock. All of the troubleshooting for a problem in the system is normally done with a Tech 2.
Things to try –
1, Get some electrical cleaner in a spray can and shoot some into the key entry area in an attempt to clean the housing.
2. Check all of the BCM connections to insure they are good and no corrosion on pins.
3. Inspect the connector that goes to the Passlock sensor in the steering column and insure all pins and connections are good.
4. You should not have to do this but, there is a Passlock learn procedure, it might be useful to do it in case somehow the data between the housing and the BCM is in error. Just make sure that the lock area is clean and all the wire connections are good before doing this or it might cause issues later with a spare key.
30-Minute Learn Procedure
1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON, vehicle will not start.
3. Observe the SECURITY telltale on dash. After approximately 10 minutes, the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes. The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.
Important: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
6. Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password.
History DTCs will self clear after 100 ignition cycles.