GM Service Manual Online
For 1990-2009 cars only

THEFTLOCK™ is designed in order to discourage theft of the radio system. THEFTLOCK™ works by utilizing a secret code in order to disable all radio functions whenever the battery power is removed. This audio system is equipped with THEFTLOCK™ if THEFTLOCK™ is displayed on the front of the radio.

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

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

Activating the Theft Deterrent Feature

The following instructions explain how to enter a secret code in order to activate the THEFTLOCK™ system. Read through all of the 9 steps before starting this procedure.

Perform the following procedure in order to activate the THEFTLOCK™ system:

    Important: The radio automatically reverts to time and you must start the procedure over at Step 4 if you allow more than 15 seconds to elapse between any steps.

  1. Create a secret code.
  2. Write down any 3 or 4 digit number from 000 to 1999. Keep this secret number in a safe place, separate from the vehicle.

  3. Turn the ignition to the ACCESSORY or the RUN position.
  4. Turn the radio to the OFF position.
  5. Simultaneously press the 1 and 4 buttons, and hold the buttons until a long dash shows on the display.
  6. Press MN/MIN. 000 will appear on the display.
  7. Press MN/MIN again in order to make the last 2 digits agree with the code.
  8. Press HR in order to make the first 1 or 2 digits agree with the code.
  9. Press AM/FM after you have confirmed that the code matches the secret code you have written down.
  10. The display will show REP letting you know that you need to repeat Steps 5 through 7 in order to confirm the secret code.

  11. Press AM-FM, and the display will show SEC. This means that the radio is secure.
  12. The theft deterrent indicator on the radio face will begin flashing when the ignition is turned to the OFF position.

Unlocking the Theft Deterrent Feature after a Power Loss

Perform the following procedure in order to unlock the theft deterrent after a power loss:

    Important: Enter the secret code as follows. Pause no more than 15 seconds between the steps.

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

If you enter the wrong code 8 times, INOP will appear on the display. You will have to wait 1 hour with the ignition in the ON position before you may try again. You will only have 3 chances to enter the correct code before INOP appears.

Disabling the Theft Deterrent Feature

Perform the following procedure in order to disable the theft-deterrent feature:

    Important: Enter the secret code as follows. Pause no more than 15 seconds between the steps.

  1. Turn the ignition to the ACCESSORY or the RUN position.
  2. Turn the radio to the OFF position.
  3. Press the 1 and 4 buttons together.
  4. Hold them down until SEC appears on the display.

  5. Press MN/MIN and 000 will appear on the display.
  6. Press MN/MIN again in order to make the last 2 digits agree with the code.
  7. Press HR in order to make the first 1 or 2 digits agree with the code.
  8. Press AM-FM after you have confirmed that the code matches the secret code you have written down. The display will show a long dash, indicating that the radio is no longer secure.

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

When the battery power is removed and later applied to a secure 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 may be used in order to remove the customer's code.

  1. Hold in the pushbuttons 1 and 4 for about 6 seconds until the display changes to SEC, with the radio in the OFF position.
  2. Important: The theft deterrent is already deactivated and no code is stored if the display changes to a series of dashes.

  3. Press the HR button.
  4. Set the first 2 digits (0-19) of the code with the HR button.
  5. Set the next 2 digits (0-99) of the code with the MN/MIN button.
  6. Press AM-FM button in order to enter the code.
  7. The theft deterrent is deactivated. A series of dashes will display, then the clock will display.

Adding Customer's Code

  1. Hold in the pushbuttons 1 and 4 for about 6 seconds until the display changes to a series of dashes.
  2. Important: The theft deterrent feature is already activated if SEC is displayed. This means the old code must be removed before entering a new code.

  3. Press the HR button.
  4. Set the first 2 digits (0-19) of the code with the HR button.
  5. Set the next 2 digits (0-99) of the code with the MIN button.
  6. Press AM-FM button in order to enter the code.
  7. Repeat the steps 3 through 5 when REP, then 000 are displayed.
  8. This confirms the customer's code, activates the theft deterrent feature, and after Step 5, displays the SEC, showing that the theft deterrent features has been activated.

The THEFTLOCK™ light will flash once every 2 seconds anytime the ignition is removed and the THEFTLOCK™ is activated. The display will show LOC and will need to be unlocked by either the customer's code or the factory backup code anytime the battery power is cycled and the ignition is applied.

Obtaining Radio Display Code (Scrambled Backup Code)

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

  1. Simultaneously press and hold the 2 and 3 pushbuttons for about 6 seconds until the first 3 digits of the display code appear.
  2. Write the numbers down.
  3. Press the AM-FM button.
  4. The second 3 digits will display.

  5. Write the numbers down.

The display returns to LOC after approximately 5 seconds, or if another button is pressed. The display code must be unscrambled in order to get the factory backup code that unlocks the radio. Call the Delco Electronics Corporation in order to obtain the factory backup code and enter the authorized account number along with the display code you have recorded.

Changing Customer's Code

The radio must be unlocked. No customer's code may be currently stored in the radio, in order to change the customer's code. The radio will display 1:00 when the radio is unlocked.

Press and hold pushbuttons 1 and 4 until the display changes, in order to determine whether or not there is a customer's code stored. There is a customer's code stored if SEC displays. There is no code stored if a series of dashes display.

Obtaining Factory Backup Code

Refer to Dealer Communications System or call Technical Assistance for unlock procedures if the customer's code is unavailable.