Our 980G has started messing up when shifting. If we have the switch in the 2 automatic position it will work 95% of the time but sometimes when going into the pile you shift into 1st but when you back out of the bank it won't shift back into 2nd and the only way to get it back into 2nd is put the top switch into the top manual switch. Not sure if its electrical or hydraulic?
I would guess Electrical, maybe a loose or bad harness connector to the speed sensors or a bad tooth on the speed sensor trigger wheel or gear. They might not even leave a code. Speed sensor signals are frequency but need to be clean, the ECM is sensitive and glitches cause trouble. There are two speed sensors so the ECM knows if you are traveling forward or reverse. If you can't find can't codes make a breakout harness and hook the sensors up to a good scope meter, travel in both directions and watch. Look for clean signals no glitches, icesicles hanging on signal or different sized signals. Hope this helps you. There are a couple of G loaders around here causing trouble and asyet unsolved. They are kicking out of gear I think. Later Bob
Check the calibration on the left brake pedal. This would be the one that also puts the tranny in to neutral. There is a modulation sensor there and if it is out of calibration, I can cause this type of problem. It might be as simple as some dirt or debris stuck under the bottom side of the pedal. This would hold it in the engaged mode, only a tiny bit, and could cause the pedal to modulate. Any signal from the modulation sensor will cause transmission not to shift. I have also experienced just switching the fuel economy switch back and forth rigorously a time or too to do away with the same problem. Not sure how these two are connected but they are, because of economy and shift points.