Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
Hi there. I am Cam.When you say the key will not unlock the door, it will not physically turn in the cylinder? If so this is a key or cylinder issue. There is nothing electronic that prevents the key from ever turning in the locks.
Does it start and run though?I am understanding that your key will not turn in the door, is that correct?
The security light may be a bad connection between the ignition cylinder and the Body Control Module (BCM), mainly at the main connector for the steering column. That you can repair by taking the connector apart, making sure there is no corrosion and putting some dielectric grease on the terminals. DO the same for the 3 pin sensor that goes around the ignition cylinder itself.