What's a radio unlock code?

Just got thru replacing ignition switch on 01 GP. Decided to replace radio since dash is tore appart. Radio has display that periodically partially works. Thought I'd just get used stock replacement off eBay. Keep seeing dialog about with or without unlock codes. Can I or can't I replace my stock radio with a stock one from another GP with out a bunch of additional hassle. What's this numer and how do you get around it or does dealer have to do something special?

Theft-Deterrent Feature
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.
The THEFTLOCK feature for the radio may be used or
ignored. If ignored, the system plays normally and the
radio is not protected by the feature. If THEFTLOCK is
activated, your radio will not operate if stolen.
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.

Activating the Theft-Deterrent Feature
The instructions which follow explain how to enter your
secret code to activate the THEFTLOCK system. It is
recommended that you read through all nine steps
before starting the procedure.
If you allow more than 15 seconds to elapse between
any steps, the radio automatically reverts to time and
you must start the procedure over at Step 4.
1. Write down any three or four-digit number
from 000 to 1999 and keep it in a safe place separate
from the vehicle.
2. Turn the ignition to ACCESSORY or RUN.
3. Turn the radio off.
4. Press the 1 and 4 buttons together. Hold them down
until “---” shows on the display. Next you will use the
secret code number which you have written down.
5. Press MIN and “000” will appear on the display.
6. Press MIN again to make the last two digits agree
with your code.
7. Press HR to make the first one or two digits agree
with your code.
8. Press AM/FM after you have confirmed that the
code matches the secret code you have written down.
The display will show “REP” to let you know that
you need to repeat Steps 5 through 7 to confirm your
secret code.
9. Press AM/FM and this time the display will show
“SEC” to let you know that your radio is secure.
With the ignition off, the THEFTLOCK LED indicator
will flash, indicating a secured radio.

Unlocking the Theft-Deterrent Feature After a
Power Loss
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 to make the last two digits agree
with your code.
4. Press HR to make the first one or two digits agree
with your code.
5. Press AM/FM after you have confirmed that the
code matches the secret code you have written down.
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 lose or forget your code, contact your dealer.

Disabling the Theft-Deterrent Feature
Enter your secret code as follows; pause no more than
15 seconds between steps:
1. Turn the ignition to ACCESSORY or RUN.
2. Turn the radio off.
3. Press the 1 and 4 buttons together. Hold them down
until “SEC” shows on the display.
4. Press MIN and “000” will appear on the display.
5. Press MIN again to make the last two digits agree
with your code.
6. Press HR to make the first one or two digits agree
with your code.
7. Press AM/FM after you have confirmed that the
code matches the secret code you have written down.
The display will show “---,” indicating that the radio
is no longer secured.
If the code entered is incorrect, “SEC” will appear on
the display. The radio will remain secured until the
correct code is entered.
When battery power is removed and later applied to a
secured radio, the radio won’t turn on and “LOC” will
appear on the display.
To unlock a secured radio, see “Unlocking the
Theft-Deterrent Feature After a Power Loss” earlier
in this section.

Long story short if you buy one that is not activated there is no problem. If you buy one that is activated you'll need the code in order to get it to work.

Thanks for write up. Peoples depth of knowledge and willingness to share continues to amaze. You guys have saved me a lot of time, money, and frustration. Much thanks and props.

Or if you can find one that is locked with a code for an unbeatable price because the seller doesnt know the code, I will help you get it unlocked.

Or else you could just install an aftermarket.

Thanks for write up. Peoples depth of knowledge and willingness to share continues to amaze. You guys have saved me a lot of time, money, and frustration. Much thanks and props.


That was all copied and pasted from your owners manual. You can find an online PDF version on GM's website.

JRadio has display that periodically partially works.

What is meant by partially works?
Thanks.