Typically what happens is the small wires coming off the ignition lock cylinder will break. The theft deterrent module then no longer sees the resistance of the chip in the key. You can verify this with an ohmmeter. Read the resistance across the chip in the key, then insert the key into the ignition. Go under the dash and read the resistance across the two white wires coming out of the steering column. These wires are encased in an orange insulation as shown in the picture below. The resistance should be the same as the key chip. If not, the wire coming off the cylinder is broken. You can either replace the ignition lock cylinder or bypass the system by installing a resistor of the same value as the key chip across the white wires coming out of the column. Please let me know if you need additional information.