How to reset security system?

Try using your spare key and see if the problem goes away ( a "bad" key can be a possible cause). If this doesn't work you would have to start diagnosing the system from scratch. I just looked on Alldata they have pretty comprehensive instructions, (look under Diagnosis and Repair then Accessories and optional equipment, then anti theft/alarm. Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect...