When I turn on my 2004 Cadillac CTS, the engine light stays on. I took it to get an oil change suspecting the problem was the oil since it WAS low. After the oil change, the engine light is Still on. I took it to Auto Zone since they test your "Check Engine" lights, anyway. He said that the problem was located in my Electronic Brake Control Module. I don't feel too safe knowing that my Check Engine light is on, and would like some guidance on how to solve this problem. Any advice will be helpful.