2002 Chevy S-10 can not communicate with computer

Now that the codes can be read, here is what it says.
" a short to ground or a short to battery has been detected in shift selonoid A". The problem I am having is the car will not shift into overdrive or lock up the converter. When you are under the car looking up at the tranny, is selonoid A on the Pass or drivers side in the tranny?
Thanks in advance.

Change 1-2 and 2-3 they are the same and come in pairs at any gm dealer. If you like you may use a DOMV and check the resistance on each one. You meter should show all 000's if it is good.
Badbo

Thanks again for your prompt reply and excellent help. Right on the money, again!

Changed both shift selonoids, filter, fluid, gasket. Drove approx 50 miles, worked great. NOW, it sounds like it is starving for fluid, will not shift unless you let off gas pedal, and down shifts at the slightest incline or speed up. What could be problem. Fluid level is right on. Also added a can of additive when re-filled, (lucas).