I have a 1994 Mercury sable 3.0 V-6 automatic trans. The transmission is doing bad things. Was driving 65 mph when the trans decided to down shift like hitting a brick wall. since then the trans wouldn't go into O/D. I've changed the trans fluid and filte wihich didn't look to bad for 165,000 miles no debris in the pan. Didn't help. whenever it's put into drive it shifts hard into gear. Sometimes the trans has to be run in D or sometimes it has to be run In O/d depends on what it wants to do. When run and shifting good threw 3 gears in D the O/D mode will freewheel when it shifts into the 3rd gear. Then sometime when it will work in O/D it will do it's down shift thing. Have had it to a trans shop to check out electronics they can't bring up nothing because it says there is no power to use the reader. Have taken the plugs out of the electronics on the trans and there is no corrosion in the connectors have cleaned grounds all around the engine compartment and battery and fuses in the engine compartment with no change.