2001 Pontiac Sunfire service light

My car has been a very good car, even with all of these miles on it. When I start my engine and put the car in drive, the head lights blink about 4 times and the service light with a wrench comes on and the day time lights go out. If I turn on the lights before I put the car in drive, it does not do it. The book reads, a problem has been detected. It does not throw out a code when you hook it up to a computer. What could it possibley be. I need to know where to start.