Anti theft

Did you replace the computer before or after this started? If before did you reprogram it to match your vehicle and the keys you have? If after and this was the reason why, you still need to program in the keys you have as they will not match the information stored in the "new" ECM but it also sounds like you will need to use a good scan tool to interrogate the SKIM module as the light staying on indicates a fault in the system, either in the transponder, antenna ring or communication lines. That cannot be tested without a dealer level scan tool.