My radio wont come on it has loc on the screen and i have no manual

dealer with vin or vehicle and proof of ownership

It is written in your owners manual. you need a code which the original owner would have written down somewhere in the manual. If no code, no radio. Only the dealer can unlock and make new code.

That is a security "feature" on GM radios to deter theft. The following instructions has had sucess with other GM vehicles. If not, only a dealer has the equipment to get past lock screen.

This works on vettes with theftlock. Try it on the tahoe and let us know....




The following procedure will give you a new code that you can use instead of your personal code. Using this new code, you can "unlock" your radio and then "re-lock" it with a new code if you wish. Prerequisites: The radio must be in LOC mode NOT in INOP mode. Let me explain. If you have activated the Theft-Deterrent feature of your radio and loose power, the radio goes
into LOC (theftlock) mode. With the ignition on, you must use the MN and HR buttons to enter you personal code in order to unlock it (The instructions are on page 3-27 in your Y2K Owner's manual). If you fail to enter the correct code eight (8) times, the radio goes into INOP
mode. You have to wait an hour with the ignition on before the radio returns to LOC mode (go for a long drive somewhere).

Procedure: 01. Turn the ignition ON (The radio displays LOC)

02. Hold down the Radio Presets 2 and 3 buttons for six seconds

03. The radio display changes from LOC to a three-digit number. Write this number down. Don't take forever, fifteen seconds max before the next step.

04. Press the AM/FM button

05. The radio display changes to another three-digit number. Write this number to the right of the first one.

06. You now have a six-digit number, the first three digits are from STEP 03 and the last three digits are form STEP 05

07. Call 1 800 537 5140

08. Press 1 then # (pound). You'll hear "Invalid Code, try again"

09. Press 139010 then # (pound). You will be asked to enter your four or six digit code followed by * (start)

10. Enter the number from STEP 6 then * (star)

11. Listen to the four-digit number and write it down. It will be repeated twice

12. Turn the ignition ON (The radio displays LOC)

13. Use the MN and HR buttons to enter the code from STEP 11

14. Press the AM/FM button. The radio display changes to SEC Your radio is now "un-locked" and usable. The Theft-Deterrent feature is STILL active! If you want to disable it, use the instruction on page 3-27 in your Y2K Owner's manual. Use the code from STEP 11 instead of your personal code. Note: This tip originated from LOTZAHP, Austin TX (credit must be given where credit is due). I verified it on an Y2K C5 with a locked radio - mine.
http://chevroletforum.com/forum/tahoe-suburban-25/help-radio-locked-8220/

Your radio is in lock mode. You need to look in your manual, and find your radio code, and the procedure to put it in.
You may have to call a dealership to get the code, or even go as far as taking the radio out. Sometimes they supply a card in the vehicle with the code, some are in the manual, some are on the back of the radio itself, and some are a dealer only thing where they plug your radio in to their equipment to unlock it.

The LOC stands for locked
You will need a code to get this radio to operate.
You will need to have the code entered at any GM dealership & have proof of ownership with your ID
It is a theft deterrent system installed on all radios these days since the 90's

Hi, my name is Ben. When LOC is displayed on the radio it indicates that power has been shut off to the radio. Probably disconnected the battery during servicing the vehicle. Once this happens, there is a code which must be entered using the buttons on the radio to make the radio able to work again. If you don't know the code, you will need to take the vehicle to a dealership service department and have them unlock the radio. Sorry, I can't help you more, but hopefully you have the information you need now. If you can find the code, sometimes it's written in the owner's manual, I can give you the procedure for entering it into the radio.

notify a dealer the loc code is part of vehicle security system-- call the dealer first they can also advise how to retrieve the radio id code which is needed for the un loc code or if u have ur manual in if is how to retrieve the radio id code

contact a gm dealer they should be able to retreve your code

You need to enter the unlock code for the radio. This should be in the user manual just inside the front cover.

Good Day,

The following procedure will give you a new code that you can use instead of your personal code. Using this new code, you can “unlock” your radio and then “re-lock” it with a new code if you wish. Prerequisites: The radio must be in LOC mode NOT in INOP mode. Let me explain. If you have activated the Theft-Deterrent feature of your radio and loose power, the radio goes into LOC (theftlock) mode. With the ignition on, you must use the MN and HR buttons to enter you personal code in order to unlock it (The instructions are on page 3-27 in your Owner’s manual). If you fail to enter the correct code eight (8) times, the radio goes into INOP mode. You have to wait an hour with the ignition on before the radio returns to LOC mode (go for a long drive somewhere).

Procedure:

01. Turn the ignition ON (The radio displays LOC)

02. Hold down the Radio Presets 2 and 3 buttons for six seconds

03. The radio display changes from LOC to a three-digit number. Write this number down. Don’t take forever, fifteen seconds max before the next step.

04. Press the AM/FM button

05. The radio display changes to another three-digit number. Write this number to the right of the first one.

06. You now have a six-digit number, the first three digits are from STEP 03 and the last three digits are form STEP 05

07. Call 1 800 537 5140 08. Press 1 then # (pound). You’ll hear “Invalid Code, try again”

09. Press 139010 then # (pound). You will be asked to enter your four or six digit code followed by * (start)

10. Enter the number from STEP 6 then * (star)

11. Listen to the four-digit number and write it down. It will be repeated twice

12. Turn the ignition ON (The radio displays LOC)

13. Use the MN and HR buttons to enter the code from STEP 11

14. Press the AM/FM button. The radio display changes to SEC Your radio is now “un-locked” and usable. The Theft-Deterrent feature is STILL active! If you want to disable it, use the instruction on page 3-27 in your Owner’s manual. Use the code from STEP 11 instead of your personal code.

I hope this helps

This came from:
http://answers.yahoo.com/question/index?qid=20070717061922AA7xMG3