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This is called CAGS, I think it stands for computer assisted gear shifting, and it's a mileage enhancing trick employed by GM. You'll be able to find the circustances under which the 1 to 4 shift is enforced in this forum or most any other Vette forum. Basically, the transmission is supposed to shift from 1st to 4th, instead of 1st to 2nd, under low load, low throttle conditions once the engine is warmed up.
If the transmission is not doing this wierd 1 to 4 shift thing it means that some good-hearted soul has disconnected the wire to the transmission. Several vendors make a "connector" that can help to keep the old plug and socket clean and supposedly has a small resistor to make the computer think the connection's still in place. I don't think the resistor matters one way or another. Also, there's no way to disable the one to four shift light other than removing the bulb from its socket.