How do I Reset the Security System in a 2000 GMC Jimmy?by David Clair
Some models of the 2000 GMC Jimmy are equipped with an anti-theft security system. If the "SECURITY" light flashes when you open the door with the ignition off, this indicates that the security system is not enabled. Resetting the theft-deterrent system arms and activates it. When the security system is activated, an alarm will sound when anyone makes an unauthorized attempt to gain access to the vehicle.
Open the driver's door.
Press the power door-lock switch to lock all the doors, with the driver's door still open. The "SECURITY" light will come on.
Close the driver's door. The "SECURITY" light will go off after about 30 seconds. The system has been reset.