GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Express 🢒 Body and Accessories 🢒 Entertainment 🢒 Radio/Audio System Operation-Theftlock

Theftlock™ Feature
    • Theftlock™ is designed to discourage theft of the radio.
    • Theftlock™ uses a secret code in order to disable all radio functions when battery power ceases.
    • You may use or ignore the Theftlock™ for the radio.
    • If ignored, the system plays normally, and the radio is not protected by this feature.
    • With Theftlock™ activated, the radio will not operate if stolen, and the indicator light next to the volume control will flash whenever the ignition is turned off.
    • When you activate Theftlock™, the radio displays LOC indicating a locked condition anytime battery power is removed.
    • If the battery looses power for any reason, the radio must be unlocked with the secret code before it will operate.

Activating the Theftlock™ Feature

Important: Read all steps before starting the procedure.

If more than 15 seconds elapse between any of the steps, the radio automatically reverts to time and you must start the procedure over from step 4.

If SEC appears on the display in step 4, the system has already been activated.

To change the code, the old code must be removed first.

In order to activate the Theftlock™ system, perform the following steps:

  1. Write down any number from 000 to 1999.
  2. Turn the ignition to the ACCESSORY or the 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 MN and 000 will appear on the display.
  6. Press and hold MN again until the last two digits agree with your code.
  7. Press and hold HR 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. SEC will appear on the display, the radio is now operable and secured.
  10. With the ignition OFF, the Theftlock™ indicator flashes.

Unlocking a Radio That Displays LOC When Code is Known

Important: Read all steps before starting the procedure.

If more than 15 seconds elapse between any of the steps, the radio automatically reverts to time and you must start the procedure over from step 4.

In order to unlock the Theftlock™ system after a power loss, perform the following steps:

    • Write down the users code.
    • Turn the ignition to the RUN position.
    • Press MN and 000 will appear on the display.
    • Press and hold MN until the last two digits agree with the code.
    • Press and hold HR until the first one or two digits agree with the code.
    • 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.
    • SEC will appear on the display, the radio is now operable and secured.

If the wrong code is entered more than eight times, INOP will appear on the display.

Wait one hour before attempting to unlock the radio again.

This time only three attempts will be allowed before INOP appears on the display.

If this happens you must wait one hour before attempting to unlock the radio again.

Unlocking a Radio That Displays LOC When Code is Unknown

Important: Starting in 1995, a factory back-up code can be used to erase the original code if it is unknown.

Have account number ready to enter when asked. Account number is your five digit dealer code followed by one of these numbers:

   • Chevrolet - 1
   • Pontiac -2
   • Oldsmobile -3
   • Buick -4
   • GMT -5
   • Cadillac -6
   • GM Canada -7
   • Saturn -8
Read all steps before starting the procedure.

If more than 15 seconds elapse between any of the steps, the radio automatically reverts to time and you must start the procedure over from step 1.

In order to unlock the Theftlock™ system when code is unknown, perform the following steps:

  1. Press and hold push 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, a three digit code will appear on the display again.
  4. Write the three digit code on a piece of paper.
  5. Call Delco Electronics at 1- 800 - 537 - 5140.
  6. Follow the computer prompts to obtain the back-up code to be used in place of unknown code.
  7. Press MN and 000 will appear on the display.
  8. Press and hold MN until the last two digits agree with the back-up code.
  9. Press and hold HR until the first one or two digits agree with the back-up code.
  10. 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 7 through 10.
  11. The display will show - - - to indicate unknown code has been removed.

If the back-up code does not unlock the radio, try reversing the first and last three digits of the display code.

If this is unsuccessful, call Delco Electronics to obtain a new factory back-up code.

Disabling the Theftlock™ Feature

Important: If more than 15 seconds elapse between any of the steps, the radio automatically reverts to time and you must start the procedure over from step 3.

In order to disable the Theftlock™ feature, enter the user code as follows:

  1. Turn the ignition to ACCESSORY or RUN.
  2. Turn the radio OFF.
  3. Press the 1 and 4 buttons together. Hold then down until SEC appears on the display.
  4. Press MN and 000 will appear on the display.
  5. Press and hold MN until the last two digits agree with the user code.
  6. Press and hold HR until the first one or two digits agree with the user code.
  7. 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 4 through 7.
  8. The display will show - - -, indicating that the radio is no longer secured.
  9. If the code is entered incorrectly, SEC appears on the display.
  10. The radio will remain secured until the correct code is entered.