Chevy Impala Theft Relearn Procedure

Problem with my 2002 Chevy Impala. Security Light Flashes on Dash Ignition was changed to allow the key to turn. Now it turns but will not start up and the Security Light Flashes. Looking for step by step instruction on how to reset the Security Codes which will allow the car to start. No other problems just the security wont let the car start up. The ignition was changed to allow the key to turn. Now it turns but will not start up and the Security Light Flashes. Looking for step by step instruction on how to reset the Security Codes which will allow the car to start. No other problems just the security wont let the car start up.

Answer:
Thank you for the tip/donation. Here is the procedure you requested....

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, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 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. Start the engine (the vehicle has now learned the Passlock Sensor Data Code and/or password). With a scan tool, clear any DTCs if needed (history DTCs will self clear after 100 ignition cycles).

Be sure to have a battery charger on the car, as this 30 minute procedure may drain the battery to a point were it will effect the programming- or cause a dead battery. The other way is to have a dealer scanner re-program the system.

Question:
2002 chevy Impala Auto 3.4L Car sometimes will not crank over when you turn key to start. Everything comes on as normal but engine will not turn over. I can rock the car back and forth move the gearshift up and down and mess with the battery cables and out of the clear blue it will start. It may not happen again for a couple of months. I am thinking maybe neutral safety switch but not for sure. BCM was replaced a couple of years ago. If switch is it under dash or on trans.

Answer:
If after it does not start, the security light is on when it wont start and the key is still on, you have a security problem. The most common cause of this is a faulty ignition cylinder. I will send you the repair procedure if you want to do this yourself. Just let me know.

There is also a CRANK RELAY in the underhood fuse block. May want to swap it with another one of same type from that block, or just replace it- they are pretty inexpensive. Do this before replacing the Passlock cylinder, and let me know what happens.

Question: What makes the ignition stop turning after removing the factory stereo the replacing it with the same stereo.
 Answer: Replacing the radio would have nothing to do with the ignition cylinder not turning. Unless something got caught in the cylinder, which is highly unlikely. Sounds like just a coincidence. Try a different key, spray WD-40 in ignition, wiggle it and try to work it free. Then the cylinder may need to be replaced.

I completed the above procedure.. The vehicle runs fine, however, the SECURITY light remains on.. ???
 That is a temporary fix. There is a problem in the system. Most likely the ignition cylinder- also known as the Passlock Sensor. Eventually the car will not start again until repaired.

Is this the same for a 2000 Chevy Cavalier, car start goes dead in two seconds alarm light flashes for 3 seconds then stays on.
 Yes, this is also the same security system, although the faulty part and re-learn are different.

The ignition cylinder can lock up if you leave the key in while you're taking the dashboard off. The dashboard will get hung on the key and bend the pins in the cylinder and you will have to replace the ignition cylinder. I have a 2001 Impala and i change ignition and It wont start but I keep try and it finally worked.
 Glad to hear it.

My 2006 Chevy impala wont start. Makes no noise when I attempt. No lights and nothing works. (Doorlocks.windows. etc) Please help!
 Start with the basics. Check for a bad battery or loose connections on the battery. Check for a bad "Crank Relay".

The security system on todays cars and trucks prevents the vehicle from being stolen. There are many variations of the system going back to the early 1990's. This warning could be on when the engine is running, indicating a fault has been detected in the system. If left un repaired, there is a good possibility that the car will eventually not start. There are several different possibilities for the cause of the warning, depending on the make / model / year of the vehicle. Anything from a bad ignition cylinder wire, to a bad cylinder to a dad Body Control Module (BCM). After market (non-factory) alarm and remote start systems can cause havoc with the factory theft system, causing this warning light, or a no start.