Hey guys. I purchased an 89 GTA a while ago and I just dropped in a motor for it ('90 formula motor). The delco radio came with the car, but it was in the trunk. When I turned the car on, it gave the old 'Loc'. Is there anything internally I can do with the radio to unlock it? I am electronically inclined, so throw what you have at me. I have an aftermarket head-unit, so I'm not going to spend money to have GM reset the radio. I just want to play around with it for a while. Even permanently disabling the lock function is an option, I just need to know how. Thanks

the only way i know how to unlock it is by pressing the mute button on the steering wheel controls

A nice GM dealer will look up the code for free...just call around.

Taken from whitebird00 over at ls1tech referring to 98-02 monsoon stereos, don't know if it'll help you or not...

"TheftLock is designed to discourage theft of your radio. It works by using a secret code to disable all radio functions whenever battery power is removed (or when the radio is removed).

You usually don't have to worry about the TheftLock feature. TheftLock is not activated when you buy a new car and most owners don't bother activating it after taking delivery. Considering how little used Monsoon head units cost, there isn't much market for stolen ones. You can tell if TheftLock is activated by the flashing red LED on the face of the radio when the car isn't running.

When TheftLock is activated, the radio will display LOC to indicate a locked condition anytime battery power is removed. If your battery loses power for any reason, you must unlock the radio with the secret code before it will operate.

Unlocking the Theft-Deterrent Feature After a Power Loss

If you know the code that was used to lock the radio then use the following instructions from the owner's manual to unlock the radio.
Quote:
Enter your secret code as follows; pause no more than 15 seconds between steps:
1. Turn the ignition on. LOC will appear on the display.
2. Press MIN and 000 will appear on the display.
3. Press MIN again until the last two digits agree with your code.
4. Press HR until the first one or two digits agree with your code.
5. Press AM-FM after you have confirmed that the code matches your secret code. The display will show SEC, indicating the radio is now operable and secure.

If you enter the wrong code eight times, INOP will appear on the display. You will have to wait an hour with the ignition on before you can try again. When you try again, you will only have three more chances (eight tries per chance) to enter the correct code before INOP appears.
If you don't know the code that was used to lock the radio then you will have to use the dealer's unlock procedure as follows. The dealer code changes over time - the one listed is current as of this posting. If it doesn't work try 08359 or search the forum for messages with a more recent code.
Quote:
1. Press and hold presets 2 & 3 for about 10 seconds until the first three digits of the display code are displayed.
2. Write the numbers down.
3. Press the AM-FM button, write down the next three numbers.
4. Call 1-800-537-5140. When asked, enter dealer code 202108, press the * button, and enter the six digit code from the radio. You will get an unlock code, write it down.
5. Go back to the car, press the HR button and set the first two numbers, press the MIN button and set the next two numbers, then press the AM-FM button. The display will show SEC, indicating the radio is now operable and secure.

To remove the code, repeat step 5. you should see --- on the radio face indicating the code is now out of the radio."

I changed my spark plugs (another gruesome story) and disconnected my battery following advice from someone who shorted out their starter when they dropped a tool on it. With my luck that would happen to me, so I disconnected the battery. Now, my radio is locked. Checked the owners manual (I know, shoulda done that before!) and it describes an unlocking sequence using a preset 6 digit number that the owner can program into the radio. I have no idea if the previous owner did that, but my radio will not respond to the first step of the process which is hitting the "set" button to start inputing numbers. Thought I would try all zeroes first, but cannot get the unlocking feature to start. Manual says to contact your dealer if you lose or forget your secret number. Has anyone dealt with this problem? Your help appreciated.

This was the only info I could find in a search. Wondering if there was any new info since 2007. My problem is that I can't even get the unlocking sequence to even begin.

when i had my stock delco deck all i did was press the mute button on the steering wheel and it unlocked....

The MUTE button worked today, radio back. I did try that at first and did not work. Thanks.

Hey all, same problem for me. 1990 Pontiac 6000 SE with a locked radio. Funny part is it has simply unlocked itself twice before after a power loss. Now it is remaining locked. Any advice would be appreciated.

Lots of great advice available but the unit appears to be a bit of a rarity as the preset buttons are not numbered and there is no MIN button.

If you hold "seek" and "scan" together you should get a 3 digit number (i.e. 456) and then hit the "am-fm" to get your second set of numbers. If this works post it and I can call it in to GMs Radio unlock hotline and get you the 4 digit unlock code. I work for a Dealership, so I have access to that information.

Thanks for the fast response to my LOC issue. Unfortunately, holding seek and scan together didn't do the trick. The steering wheel is covered in buttons as well and some have had success with the mute button but that didn't work for me either. I might end up at the dealer soon on this one...

The conclusion to my issue was as simple as disconnecting the battery cables and letting the lovely 6000 relax for awhile (after some concerning non-related electrical issues came to light...). Reattached the cables and started the car and the radio worked again. Am I just that lucky or is the 6000 just that good?

Nice info

So I have a 94 TA that has been in storage for a while.The radio locked up and I had been unable to unlock,UNTIL, I read this thread.
So here I am.I tried the advice above and I left the key on for an hour.It finally gave up the six numbers as suggested.I tried the 800 number and cant seem to get anything?It asks for a division digit.I tried 1 and 2 and it does nothing.If I enter the code given above it says invalid.What am I doing wrong? The digits on my radio that I get are 912925. Help??

So I have a 94 TA that has been in storage for a while.The radio locked up and I had been unable to unlock,UNTIL, I read this thread.
So here I am.I tried the advice above and I left the key on for an hour.It finally gave up the six numbers as suggested.I tried the 800 number and cant seem to get anything?It asks for a division digit.I tried 1 and 2 and it does nothing.If I enter the code given above it says invalid.What am I doing wrong? The digits on my radio that I get are 912925. Help??

None of these steps work for mine so its now going to be a paper weight, and im putting a new deck in

This only works if the car has searing wheel controls.

I have a 2004 Chevy Impala and all of these steps you state do not work at all. Holding down 1&4 or 2&3 or min and hr does absolutely nothing.

I have had my 1989 trans am gta for a while now I for the longest time I had an after market stereo in it. Well I have taken the after market radio out and pit the stock one back in. But when I turn the car on nothing happens. I get nothing no power to the head unit. And it worked perfectly fine befor. Jut wanted to install a DVD player in the car. Any ideas guys I really want to put everything back to stock. I am trying to enter it into car shows.

Its odd but every car line has diff steps to unlock the radios.
I have 89 and 92 sevice manuals and If I remember correctly the 89 radio has diff steps from the 92 radios.. soo It could even change from year to year.

A FACTORY service manual for your car has the information you need.

Power to the HU is the car's responsibility, not the radio. If you are getting LOC on the screen, the only way to unlock it on an 89 GTA is to press the MUTE button on the steering wheel.

You probably had to change the wiring harness when you put in the aftermarket and now have to re-install the old harness. Some of these Delco's also CODE LOCK when removed and you need to UNLOCK before they will work. If you have a service manual the instructions are included or do an internet search on the John Bain web site.