The error code means the radio EPROM chip and the Car computer Vin number does not match.The dealer is the only one who can reprogram the radio to match the vehilce vin #.Or you can remove the radio open the cover and remove the eprom chip.There are video's on You Tube that can show you how to do this.
-------------------here is factory unlock proc------------------
This is the process for the CD deck. I assume it's the same for any 88-90 deck with the DelcoLok system. It may also work with 90+ DelcoLok I units.
1. Press and hold presets 2 and 3 for about 5 to 10 seconds until you
get 3 digits on your display. This is the first 3 of 6 digits you will
need, so write 'em down. (mine were 881)
2. After doing step one and writing down the code, immediately press the
AM/FM button to get the last 3 of the 6 numbers you'll need, and write
'em down. (if you wait too long between steps 1 and 2 and the LOC code
displays again, just start over). (mine were 322)
3. Call this number, it's a prerecorded message, so don't worry about
having to talk to anyone...1-***-***-****. The voice will ask if you're
calling for Chevy, Pontiac, Cadillac, etc... When you hear this,
press 1 for chevy, followed by 02107and hit the * key. (i.e. 102107*) He'll ask you for the 6 digit code that you've written down.(mine was 881 322) Enter that and press the * key. He will then give you a code,(mine was 810 891)
4. To unlock the radio:
A. Turn the ignition on.
B. Press “SET” (000 appears on display).
C. Press “SEEK until the first digit of the code appears.
D. Press “TUNE" until the second and third digits
E. Press "AM-FM" (000 appears on display).
F. Press “SEEK” until the fourth digit of the code appears.
G. Press “TUNE” until the fifth and sixth digits of the code appear.
H. Press "AM-FM". Now the radio can be turned on.