Q: Pass key fault is on

The keys on these vehicles have a computer chip inside them that is programmed to the vehicle. It is possible that the vehicle may have been attempted to start with a key that is not programmed to the car, therefore going into theft mode. It is also possible that the theft module in your vehicle has gone faulty. I would recommend having a diagnostic performed by a qualified technician who is proficient with General Motors vehicles. Many times the repair of this issue involves reprogramming of either the key, theft module, or both. Once the cause of the issue has been found, have the repair done as soon as possible in order to be able to use your vehicle again.