The service security device flashes across dash. Starter disabled comes on.

Hello, The vehicle is being shut off because it thinks it has been stolen. Have you tried using the remote to unlock the vehicle? Also, the key may be bad, and using the spare key may help. If the key is not bad, the error could be anywhere in the security system, and diagnostics will be necessary to find the cause. If you would like further information, let me know, but if you prefer to have a shop handle diagnosis and repair, the list here has all of the certified shops in your area: http://repairpal.com/cadillac-within-10-miles-of-seattle-washington-98118