Security system

2000 Blazer, 4 wheel Dr. V6 Vortex engine W/50,000 mi. Was running fine, now the security light stays on all the time, even if ignition isn't on. Wares the battery down. When it is charged it will start, but the security kicks in and shuts off the fuel, and it shuts down. The truck has always ran fine, has very low miles. At this point if it needs work, I would have to have it towed to the garage. Is there a code or over ride to temporailly fix this problem. My truck has been down for two months. Help Thanks