I own a 2003 Pontiac Grand Prix and after replacing the batter, my Theft Loc device triggered and locked out my radio reading LOC also. I followed the below instructions and it worked perfectly. Following the input of the below info my screen read SEC and then I hit Power On and it worked!!!

Thanks again!!!

Quote Originally Posted by kdunville
Try this, it worked for my 1998 Sunfire and a 1975 Monte Carlo.
Press & hold the 2 & 3 buttons @ the same time for about 10 seconds; a 2 or 3 digit code will appear, write this # down,press & hold the am/fm button for about 10 seconds: another code will appear, write this # down, then call 1-800-537-5140 and enter 202108 followed by the # key, then enter the #'s that you wrote down from your radio followed by the * key. The call will give you a 3 or 4 digit override code. Write this code # down so you have it if you ever need it again. Enter this # into your radio following the instructions in your owners manual. If you get an override code that starts with 0, you drop the 0 when entering the code into your radio.
If you don't have an owners manual, try this, press & hold the hour button until the first 2 digits of your code come up, then press & hold the minute button until the last 2 digits show. Then press the am/fm button. This should reset your stereo. It did mine.
Hope you find this helpful.