From the inter web…
Step-by-step unlock procedure:
1) Turn on the vehicle: and then turn on the radio. The display will show "LOC" if it's locked, or "InOP" if too many wrong codes were entered.
2) Get the Radio ID code:
3) Press and hold preset numbers 2 and 3 until a three-digit code appears. Write this code down.
4) Press the AM/FM button. A second three-digit code will appear. Write this down as well.
You now have a six-digit code.
6) Call the GM Radio Hotline: Dial 1-800-537-5140. This is an automated system.
7) Enter the required codes:
-Enter the dealer code or authorization code (if prompted), followed by the * key.
-Enter the first three-digit code you wrote down, followed by the * key.
-Enter the second three-digit code you wrote down, followed by the * key.
-Receive and enter the unlock code: The system will provide a four-digit radio unlock code.
8) Unlock the radio: Using the "Hour" and "Minute" buttons on your radio, enter the four-digit code.
9) Confirm unlock: Press the AM/FM button to unlock the radio.
What to do if "InOP" appears:
If your radio shows "InOP," it means too many wrong codes have been entered recently. You will need to wait for up to an hour with the radio powered on before you can try again.
BTW, adapters can be purchased that plug between the new radio and the Fiero radio connector. Try ReplacementRadios.com. This way you don’t need to cut and splice wires. You may need the antenna adapter. It usually comes with the adapter but double check.
[This message has been edited by Mike in Sydney (edited 09-01-2025).]
