GM Theftlock Radio Issues

Auto Care Advice

Do you see "LOC" or "INOP" displayed on your GM radio? If so, please see the article below for important information about the GM Theftlock Radio System.

To unlock the Theftlock system when the user code is unknown, perform the following steps:

  1. Press and hold buttons 2 and 3 until a three digit code appears on the display.
  2. Write the three digit code on a piece of paper.
  3. Press the AM/FM push button and a second three digit code will appear on the display.
  4. Write the second three digit code following the first three digit code. (Don't worry if both three digit codes are the same, this happens sometimes.)
  5. You will need this six digit code in order to obtain the factory back-up code for your radio. Your local GM dealer may provide this service free of charge. Find one near you >> Buick, Cadillac, Chevrolet, GMC.
  6. With the 4 digit factory back-up code in hand perform the following steps.
    1. Press the Minute button and 000 will appear on the display.
    2. Press and hold the Minute button until the last two digits agree with the back-up code.
    3. Press and hold the Hour button until the first one or two digits agree with the back-up code.
    4. Press the AM/FM push button after you have confirmed that the code matches the factory back-up code you wrote down. If "SEC" appears on the display, the radio is now operable and secured. (The original, unknown user code is still stored in the radio.) If "REP" appears on the display, repeat steps 1 through 4.
    5. If the display shows "- - -" this indicates that the unknown user code has been removed. (The "- - -" will go off after a short time, once the Theftlock code has been erased. Now, the Theftlock has been disabled and the radio should function normally.)

If the wrong user code is entered more than eight times, "INOP" will appear on the display. If this happens, wait one hour—with the key in the accessory position and the radio on—before attempting to unlock the radio again. After clearing the "INOP" message, you only have three attempts before "INOP" appears on the display again.

What Is the Theftlock System?

The Theftlock system was designed to discourage theft of the radio. With the Theftlock active, the radio displays "LOC," which indicates a locked condition any time battery power is lost or removed. When "LOC" is displayed, the radio must be unlocked with the user or factory back-up code before it will operate again.

You may use or ignore the Theftlock system for the radio. If Theftlock is not activated, the radio plays normally and is not protected by this feature.

With Theftlock activated, the indicator light next to the volume control will flash whenever the ignition is turned off and the radio will not operate if stolen.

Starting with 1995 models, a factory back-up code was created, which can be used to unlock the radio and erase the user code if it is unknown. Some later model vehicles read the VIN during programing and no longer use the Theftlock System.

(Hint: If the radio display is not working and you think the radio may be locked, you can shine a flashlight onto the radio display in order to see the messages, numbers, and to perform any of the Theftlock functions.)

Activating the Theftlock Feature

To activate the Theftlock system, perform the following steps:

  1. Write down any number from 000 to 1999 (user code).
  2. Turn the ignition to the ACCESSORY or RUN position.
  3. Turn the radio OFF.
  4. Press the 1 and 4 push-buttons together. Hold them down until "- - -" shows on the display.
  5. Press the Minute button and 000 will appear on the display.
  6. Press and hold the Minute button again until the last two digits agree with your code.
  7. Press and hold the Hour button to make the first one or two digits agree with your code.
  8. Press the AM/FM push button after you have confirmed that the code matches the code you wrote down. If "REP" appears on the display, repeat steps 5 through 8.
  9. When "SEC" appears on the display, the radio is operable and secured.

Unlocking a Radio That Displays "LOC" When the User Code is Known

To unlock the Theftlock system after a power loss, perform the following steps:

  1. Write down the user code.
  2. Turn the ignition to the RUN position.
  3. Press the Minute button and 000 will appear on the display.
  4. Press and hold the Minute button until the last two digits agree with the user code.
  5. Press and hold the Hour button until the first one or two digits agree with the user code.
  6. Press the AM/FM push button after you have confirmed that the code matches the one you wrote down. If "REP" appears on the display, repeat steps 3 through 6.
  7. When "SEC" appears on the display, the radio is operable and secured.
  8. If the display shows "- - -" this indicates that the user code has been removed. (The "- - -" will go off after a short time. Once this happens, the Theftlock code has been erased, Theftlock has been disabled, and the radio should function normally.)

Disabling the Theftlock Feature

To disable the Theftlock feature, enter the user or factory back-up code as follows:

  1. Write down the user or factory back-up code.
  2. Turn the ignition to ACCESSORY or RUN.
  3. Turn the radio OFF.
  4. Press the 1 and 4 buttons together. Hold then down until "SEC" appears on the display.
  5. Press the Minute button and "000" will appear on the display.
  6. Press and hold the Minute button until the last two digits agree with the user or factory back-up code.
  7. Press and hold the Hour button until the first one or two digits agree with the user or factory back-up code.
  8. Press the AM/FM push button after you have confirmed that the code matches the one you wrote down. If "REP" appears on the display, repeat steps 5 through 8.
  9. The display will show "- - -", indicating that the radio is no longer secured. (The "- - -" will go off after a short time. Once this happens, the Theftlock code has been erased, Theftlock has been disabled, and the radio should function normally.)

If the code is entered incorrectly, "SEC" appears on the display.
The radio will remain secured until the correct code is entered.

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