GM Service Manual Online
For 1990-2009 cars only

Theft Deterrent Feature

The radio has this feature it shows THEFTLOCK on its face. THEFTLOCK® is designed to discourage theft of the radio. It works by using a secret code to disable all radio functions whenever battery power is removed.

If THEFTLOCK® is active, the THEFTLOCK® indicator will flash when the ignition if OFF.

The THEFTLOCK® feature for the radio may be used or ignored. If ignored, the system plays normally and the radio is not protected by the feature. If THEFTLOCK® is activated, the radio will not operate if stolen.

When THEFTLOCK® is activated, the radio will display LOC to indicate a locked condition anytime the battery power is removed. If the battery loses power for any reason, you must unlock the radio with the secret code before it will operate.

Activating the Theft Deterrent Feature

The instructions which follow explain how to enter a secret code to activate the THEFTLOCK® system. It is recommended that you read through all nine steps before starting the procedure.

  1. Write down any three or four-digit number from 000 to 1999 and keep it in a safe place separate from the vehicle.
  2. Important: If you allow more than 15 seconds to elapse between any of the steps, the radio display will automatically revert to time and you must start the procedure over at Step 4.

  3. Turn the ignition to the ACC or RUN position.
  4. Turn the radio off.
  5. Press the 1 and 4 buttons together. Hold them down until - - - shows on the display. Next you will use the secret code number which has been written down.
  6. Press MIN and 000 will appear on the display.
  7. Press MIN again to make the last two digits agree with the code.
  8. Press HR to make the first one or two digits agree with the code.
  9. Press AM-FM after you have confirmed that the code matches the secret code that was written down. The display wills how REP to let you know that you need to repeat steps five through seven to confirm the secret code.
  10. Press AM-FM and this time the display will show SEC to let you know that the radio is secure. The indicator by the volume control will begin flashing when the ignition is turned OFF.

Unlocking the Theft Deterrent Feature after a Power Loss

Enter the secret code as follows, pausing no more than 15 seconds between steps:

  1. LOC appears when the ignition is ON.
  2. Press MIN and 000 will appear on the display.
  3. Press MIN again to make the last two digits agree with the code.
  4. Press HR to make the first one or two digits agree with the code.
  5. Press AM-FM after you have confirmed that the code matches the secret code that was written down. The display will show SEC, indicating the radio is now operable and secure.

If you enter the wring code eight times, INOP will appear on the display. You will have to wait an hour with the ignition before you can try again. When you try again, you will only have three chances to enter the correct code before INOP appears.

Disabling the Theft Deterrent Feature

Enter the secret code as follows, pausing no more than 15 seconds between steps:

  1. Turn the ignition to the ACC or RUN position.
  2. Turn the radio off.
  3. Press the 1 and 4 buttons together, Hold them down until SEC shows on the display.
  4. Press MIN and 000 will appear on the display.
  5. Press MIN again to make the last tow digits agree with the code.
  6. Press HR to make the first one or two digits agree with the code.
  7. Press AM-FM after you have confirmed that the code matches the secret code that was written down. the display will show - - -, indicating that the radio is no longer secured.

If the code entered is incorrect, SEC will appear on the display. The radio will remain secured until the correct code is entered.

When battery power is given to a secured radio, the radio will not turn on and LOC will appear on the display.

Removing Customer's Code

Important: Either the Customer's code or the factory backup code can be used to remove the customer's code.

  1. Turn the ignition to the ACC or RUN position.
  2. With the radio off, hold the pushbuttons 1 and 4 for about six seconds until the display changes to SEC.
  3. Important: If the display changes to - - -, the theft deterrent is already deactivated and no code is stored.

  4. Press the HR button.
  5. Set the first two digits (0-19) of the code with the HR button.
  6. Set the first two digits (0-99) of the code with the MIN button.
  7. Press AM-FM button to enter the code.
  8. The deft deterrent is deactivated, - - - is displayed and then the clock is displayed.

Adding Customer's Code

  1. Turn the ignition to the ACC or RUN position.
  2. With the radio off, hold the pushbuttons 1 and 4 for about six seconds until display changes to - - -.
  3. Important: If SEC is displayed, the theft deterrent feature is already activated. This means the old code must be removed before entering a new code.

  4. Press the HR button.
  5. Set the first two digits (0-19) of the code with the HR button.
  6. Set the next tow digits (0-99) of the code with the MIN button.
  7. Press AM-FM button to enter the code.
  8. When REP then 000 are displayed, repeat steps three through five. This confirms the customer's code, activates the theft deterrent feature, and after step five, displays the SEC to show the theft deterrent feature has been activated. Anytime the ignition is removed and the THEFTLOCK® is activated the THEFTLOCK® light will flash once every two seconds. Anytime battery power is cycled and ignition is applied, the display will show LOC and needs to be unlocked by either the customer's code or the factory backup code.
  9. Important: If - - - is displayed after pressing AM-FM, the customer's code has not been entered.

Obtaining Radio Display Code (Scrambled Backup Code)

Important: In order to display this code, the radio should be in LOC mode or have SEC displayed before proceeding.

  1. Press and hold pushbuttons 2 and 3 for about six seconds until the first three digits of the display code are displayed.
  2. Write the numbers down.
  3. Press AM-FM button. The second three digits are displayed.
  4. Write the numbers down.

After approximately five seconds, or if another button is pressed, the display returns to LOC. The display code must be unscrambled to get the factory backup code that unlocks the radio. To do this, call the Delco Electronics Corporation phone number and enter the authorized account number along with the display code you have recorded.

Changing Customer's Code

To change the customer's code, the radio must be unlocked and no customer's code can be currently stored in the radio. To determine whether or not there is a customer's code stored, press and hold the pushbuttons 1 and 4 until the display changes. If SEC is displayed, there is a customer's code stored and it will have to be removed. Refer to Removing Customer's Code in this section. If - - - is displayed, there is no code stored and a new code can be added.

Obtaining Factory Backup Code

If the customer's code is unavailable, refer to Dealer Communications System for unlock procedures or call Technical Assistance.