Code 12 means you don't have a thing to worry about . Everything is normal . Actually the 12 does mean something, but it is NOT a problem code. I don't have my troubleshooting book here & can't remember exactly what it does mean.
You can buy a Haynes repair manual ($15.00) for your ride and it will explain all the codes.
Just saw the above post. Because the motor is not running you get the code 12 so it is OK.
72 El Camino
[This message has been edited by rick (edited 02-23-2000).]