Chevy S-10 Security Light problem

Hello, I have a 2001 Chevy S-10, with a 4.3 litre votec engine. I've always had problems with security lite coming on at an particular time. A VT dealership soldered a wire somewhere and changed the lock cylinder, with same key cut. It has 71,000 miles on it and seems to happen more as the weather gets colder. Since I live in the Northeast. What usually happens is it will come on when started drives. This happens several times, drivers seat belt on. I've try ed without the seat belt, still happens, this goes on for two weeks and then when I get in to start it the security light flashes, which means I have to shut it off and wait 15 minutes, then it starts and doesn't happen for another period of time. I know it cuts out the fuel pump in the tank when this occurs. I've even called Chevy they can't help me, can anyone else?