Autozone employees in this newsgroup please read this: You cannot use the "paperclip method" to read error codes in hybrid OBD 1.5 systems. You can damage people's cars when you attempt do so. Mechanics in this newsgroup please print this out and drop it by the Autozone in your community the next time you go there for parts so hopefully they won't damage someone else's car.
I am convinced that Autozone should stop reading codes and instead refer people to local mechanics to perform this service.
In regards to my previous post of my 1994 Corsica having very high voltage, my mechanic told me that when Autozone used the paperclip method to attempt to read my OBD port, they did it wrong and damaged the PCM. When he (my mechanic not Autozone) plugged his scantool in, it indicated a stored code of a PCM failure. He said this is also why my radiator fan keeps coming on and off all the time when the engine is cool. (The coolant temperature sensor throws the signal to the PCM which tells the fan to turn on)
What he told me is this: My Chevy Corsica is a 1994. In that year, they neither used an OBDI nor an OBDII system. Instead they used a hybrid system commonly referred to as the "OBD 1.5" which cannot be read by sticking a paper clip into the connector like they do on the OBDI systems.
I heartily recommend that none of you take any 1994-1995 vehicles that use the "OBD1.5" system to Autozone to have the codes read. I have investigated and found that the Autozone store in my community is not equipped with a scantool that is capable of reading the hybrid "OBD 1.5" systems. I assume that is also true of all other Autozone stores. Apparently Autozone is not aware of the differences in these OBD systems and consequently is not able train it's employees to properly identify the type of OBD system prior to attempting to read codes. When the Autozone employee stuck the metal device that resembles a key into my OBD socket, he couldn't get the light to flash on the dashboard so he took a paper clip and started touching the wires together on the OBD socket and nothing would happen. He then told me that I should just take it to the dealer. It was about that time that my radiator fan began cycling off and on intermittently when the engine is cool and still does today, and this high voltage electrical surge problem began occurring. My mechanic said that he believes that Autozone crossed the 12 volt line into the OBD data line and damaged the PCM when they were touching wires together with the paper clip in an attempt to read codes.