The security control stays on?

Persistent issues with the security system in your 1999 Chevrolet Suburban can be frustrating and difficult to diagnose. If the security light remains on, indicating an issue with the vehicle's anti-theft system, here are some additional steps and considerations to address the problem:

Resetting the System: Try resetting the security system by disconnecting the battery and leaving it disconnected for about 15-30 minutes. Reconnect the battery and see if the security light goes off. Sometimes, a system reset can clear minor glitches in the security system.

Passlock System: The security system in your Suburban is likely the Passlock system, which relies on a sensor in the ignition cylinder and the ignition key. The Passlock system can sometimes have issues with the sensor, causing the security light to remain on.

Passlock Sensor Replacement: If the Passlock sensor is faulty, it may need to be replaced. It's possible that the previous replacements did not address the root cause of the issue.

Key Programming: Ensure that the new keys and the ignition system have been correctly programmed to work together. Incorrect programming could trigger the security system.

Wiring Inspection: Conduct a thorough inspection of the wiring related to the Passlock system, looking for any signs of damage or wear. Damaged wiring could cause the security system to malfunction.

Security Module: There could be a problem with the security module itself. If all other components and connections have been verified, the security module might need replacement.

Aftermarket Accessories: If any aftermarket accessories, such as remote starters or alarms, have been installed, they could be interfering with the security system. Consider removing them temporarily to see if the issue persists.

Technical Service Bulletin (TSB): Check if there are any relevant TSBs or recalls issued by Chevrolet for the specific security system issue in your Suburban. Sometimes, manufacturers release TSBs to address common problems.

You are correct. It shuts off fuel and spark to the engine. I hate to say it but the only place that I know of that has the proper test equipment to locate the problem is a dealer.

I don't believe the BCM will cause this type of problem. I believe it has to do with the sensor either in the key or steering column.

What have the dealers done thus far?

It sounds like you have the same type of luck I do. Honestly, I believe there is a short in the security system and not the BCM.

User notes: This happens to me and it was the coil. Changed starter and it was good