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car tech, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 3332
Experience:  25 years as shop owner and master tech
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2004 Cadillac DeVille: says Locked - Theftlock active

Resolved Question:

2004 Cadillac DeVille. I replaced the radio with one of the same type. Now it says Locked - Theftlock active. How do I unlock it?
Submitted: 6 years ago.
Category: Cadillac
Expert:  car tech replied 6 years ago.

The "Theftlock" theft deterrent system is a feature on all base and uplevel radios. There is no need to program a security code into the radio as in past model years. The theft deterrent system now utilizes class 2 serial data to determine if the radio is in the appropriate vehicle. Each time the radio receives the "run" power mode message, it compares the VIN information it has stored to the VIN information received from the dash integration module (DIM) on the class 2 serial data circuit. If a mis-match occurs, the radio display will indicate to the user the radio is locked. Once this takes place, a DTC will set, the radio will not respond to any button presses and become inoperative. The two scenarios able to cause this condition are:

  1. A radio is installed from another vehicle
  2. The DIM is replaced and not properly setup with the correct VIN information for that vehicle

The only way to unlock the radio is by using a scan tool. Always refer to the table in this section to diagnose the "Theftlock" DTC for further information.

Customer: replied 6 years ago.
Relist: Incomplete answer.
Expert:  car tech replied 6 years ago.
how is the answer incomplete you need to have a scanner to unlock this model unless you have the original code from the car the radio came from you need to take it to someone that has a tech 2 scanner to get it unlocked
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