This procedure will correct all RADIO THEFTLOCK concerns for the vehicles listed. Please read the following carefully! There are time limits associated with some of these steps. Therefore, if the directions are not followed properly, unnecessary wait time will occur. The mode the radio theft deterrent system is in will determine which steps to be followed.

The theftlock theft deterrent feature in some models includes an LED indicator light that will blink when the ignition is off and the unit is in the secured state.

Radio display definition:

• LOC: Means the radio is locked and there is a customer code stored in the radio.
• InOP: Means too many wrong codes have been entered and the radio must be left powered up to 1 hour with battery and ignition applied before 3 more attempts can be made
• SEC: Means there is a customer code stored, but the radio is unlocked
• ---: Means there is no customer code stored and the radio is unlocked
• REP: Means the customer code has been entered once, and the radio now wants the code repeated to verify the code was entered correctly the first time.

Index of procedures:

A. Retrieving scrambled back-up code from unit

B. Retrieving back-up code from computer (authorized dealers only)

C. Unlocking/Deactivating unit with back-up code or customer code

D. Removing customer code

E. Adding customer code

F. Changing customer code

G. InOP second level condition


A. Retrieving scrambled back-up code from unit - with battery and ignition voltages applied and unit power is on.

If the unit is in the locked condition (LOC is displayed), proceed to step 2. Otherwise, press and hold presets 1 and 4 for about 4 seconds. The display will show either SEC or ---.
Press and hold presets 2 and 3 for about 6 seconds until the first 3 digits of the display code are displayed. Write the numbers down.
Press the AM_FM button and the second 3 digits of scrambled code are displayed. Write the numbers down. The unit will revert to the initial display, prior to code retrieval sequence, after approximately 5 seconds or if another button is pressed. Note: If after depressing the AM-FM button the display does not change, your second set of 3 digits will be the same as the first 3 digits. (Example; if 123 came up first, your scrambled code will be 123123.)


B. Retrieving back-up code from computer (authorized dealers only) - scrambled code and authorized lock account number must first be obtained.

GM dealerships- your authorized lock account number is made up by the corresponding digit for your controlling car division preceding your 5-digit GM- dealer code. For example, if your GM-dealer code is 01234, and your controlling car division is Chevrolet, then your authorized lock account number would be 101234. 1- Chevrolet/Geo 2- Pontiac 3-Oldsmobile 4-Buick 5- GMC 6-Cadillac 7- Canada 8 -Saturn 1991-1999 with Delco radios . AC-DELCO Shops- Your authorized lock account number is made up by a 9 & 0 followed by your 6 digit AC-Delco account number. For example, if your AC-Delco account number were 123456, then your authorized lock account number would be 901123456.
Dial 800-537-5140 and listen to the phone prompts. Enter your authorized lock account number followed by an asterisk (*). The next prompt will be your scrambled code that was obtained from step A, followed by an asterisk (*). The computer will respond back with 4 or 6 digit back- up code.


C. Unlocking/ deactivating unit with back-up code or customer code - with battery and ignition voltages applied and radio power off.

Press the HR button until the LOC disappears and OOO appears on the display. Note: If the display does not change from LOC to 000 the unit is probably in the InOP stage, see Step G.
Set the first two digits (01-19) of the code with HR (hours) button.
Note: As if you[rsquo ]re setting the time of day you will not see the 0 in the far left side. Example; if the first two digits of your code is 02 you will scroll with the HR button until 2 appears on the display.)
Set the next two digits (00-99) of the code with the MIN (minute) button.
Press the AM-FM button to enter the code. The radio will now be unlocked and the display will change to the clock. Continue with the following steps to deactivate the theft deterrent.
Press the HR button until display changes 000.
Repeat steps 2-4 above to remove previous code and deactivation the theft deterrent system. Note: If the backup code received from the computer does not unlock the radio, one possibility is that the first 3 digits of the scrambled code from the radio (Step A) are reversed with second 3 digits. Example; if the scrambled code is 123 456, then it may actually be 456 123. Use Step B retrieve a new backup code.


D. Removing customer code - with battery and ignition voltages applied and radio off.

Depress presets 1 and 4 for about 6 seconds until the display changes to "SEC". If the display changes to --- there is no code stored.
Press the HR button until display changes to 000
Set the first two digits (01-19) of the code with HR button. Note: As if you[rsquo ]re setting the time of day you will not see the 0 in the far left side. Example; if the first two digits of your code is 02 you will scroll with the HR button until 2 appears on the display.
Set the next two digits (00-99) of the code with the MIN (minute) button.
Press the AM-FM button to enter the code. The theft deterrent system will now be deactivated and customer code removed. The display will show --- and then change the clock.


E. Adding a Customer Code - with battery and ignition voltages applied and radio power off.

Press and hold presets 1 and 4 for about 6 seconds until the display changes to ---
Press the HR button until the display changes to 000
Set the first two digits (01-19) of the code with the HR button.
Set the next two digits (00-99) of the code with the MIN button
Press the AM-FM button to enter the code
When "REP" then 000 is displayed, repeat steps 3 through 5 before display changes back to clock. This confirms the customer code and activates the theft deterrent system. The display will then show SEC for secured.


F. Changing customer mode

When changing a code in a unit that has already had one programmed, the original will have to be removed first. If the radio is unlocked follow step D to remove and deactivate the first code.
Follow step E to reenter a new code. Note: If the unit is in LOC the appropriate steps must first be followed.


G. INOP second level lock condition

After eight initial failed unlock attempts, the unit will be in a second level lock condition and become inoperative for over 1 hour. Any further code inputs during this hour (or depressing any buttons) will cause the display or indicate InOP for about 15 seconds before returning to LOC. The unit will still be inoperative. To reset to the normal locked (LOC) condition, battery and ignition voltages must be continuously present for over 1 hour continuously. Do not attempt any radio entries or functions during this time-out period.

After the unit is brought back to the normal locked condition, the correct unlocking procedures can be followed. Following every three unsuccessful entries the unit will return to the inoperative state (InOP) for another 1-hour period.

Recommendation/Instructions:

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.