Security light

This is a tough one, because the keys are coded to the starter (so the car can't be stolen with a filed key) typically the car has to go to the nearest GM dealer for a security system recoding. Did the battery die on the keyless entry (keychain) fob? Are the lock or unlock buttons stuck or damaged on the fob? You can try taking the battery out and try starting the car with the key, if that doesn't work get it to the dealer before the immobilizer renders the starter useless. Best of luck

I should reiterate, take the battery out of the FOB not the car itself.

See my answer to Monica, dated April 22, 2016. I only know this from experience and am not a mechanic!

This is the complete relearn procedure, it should reset in 10 mins. but could take a little more than 30 minutes but easy to do. Your ignition has 4 positions 1.Off 2.ACC 3.On 4.Start (Cranks over & springs back to 3.On) Step 1 – Attempt to start the vehicle, this is the "start" position. It will crank, and start for 1-2 seconds then stall. The security light will be on or flashing. Leave the key in the ‘on’ position for 10-11 minutes, then the security light will stay solid or go off. Step 2 – Turn the key to the ‘off’ position for no less 10 seconds. Attempt to start the vehicle. If it runs at this point then you have reset your passlock. If the problem persists you can continue repeat Step 1 two more times. Make sure turn the key to the ‘off’ position for 10 seconds before each 10 minute cycle. Hopefully your car is running by now Step 3 – The vehicle is now ready to relearn the proper code. Turn the key ‘off’ for 15 seconds and then ‘crank’ the vehicle. it should start back up now. The security light might stay on solid for several minutes afterwards.

here is the answer,Past this to your url http://www.bergerweb.net/PasslockFix

The security light staying on when you drive is an indication the system noticed a fault that needs to be diagnosed. I would try to replace the key first. Second if it continues replace the key cylinder. A cylinder replacement requires a system reset by cycling through the reset procedure 3X. If these don't fix it then the problem is in the wiring.