My 2002 Tahoe's security system is staying on when I turn off the vehicle. It starts up fine and when it's running the sound turns off but when I turn the vehicle off, the lights flash and the dong dong will not stop. I have been disconnecting the battery so that it doesn't drain but can't find the problem to solve it. I've checked all the doors and windows. Has anyone else had this issue?

 

Need a scan of the body codes to see what the system is seeing. P code scan is not enough.