Does the light come on steady, or does it flash? On steady for a few moments and then going out means the theft system is working properly. Flashing means there is a problem, either the chip in the key is no good or not programmed, or the transceiver for the system is not working. You may also want to check the battery with a volt meter, it may be just strong enough to turn the lights on, but too weak to energize the starter. The computer won't turn on unless it has over 10 volts to it.