Many of you responded to my previous post regarding my 94 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 "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 "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 and still does today, and this high
voltage electrical surge problem began occurring. My mechanic said that
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.