OBD1 are codes are not standardized. You must look at the manufacturer's code for this particular model.
Classic Chilton and Hayes manuals will normally have some of these code meanings incorrect.
Your trouble seems to be in the temperature sensing circuitry when the fans are on as you have stated. It could be the fans relay (typically solid state) is not giving the expected resistance during the on condition. I don't think your problem has anything to do with the transmission.
Best i was able to find is this:
http://www.troublecodes.net/GM/
Post edited by: jmborchers, at: 2008/09/14 01:54