Picked up a surplus low hour (2000) 720 VHP last fall, had it hauled back to road system and dropped off at my shop, took it around the yard a few times and then parked it for the winter. Now it doesn’t want to engage in Forward or Reverse. We had an issue before loading it on the barge where there was no power to the transmission controller (gearco 8400 with the pulser lever and F/N/R lever). Turned out the battery solenoid that provides power to trans failed, so it got a jumper to bypass it and everything worked fine. (Have to turn off master to shut off trans control module) The transmission controller indicates the gear selected, green light etc. Won’t move at all in either direction. Sight glass has fluid. Occasionally if the key is off with just the transmission controller powered up I can get the E 2.0 code indicating an open circuit in solenoid 2. But that never flashes when the engine is running. The diagram I found for the wiring shows the solenoid relay that goes to a 15 amp fuse that then feeds a varistor which goes to the solenoids. But I can’t seem to locate that fuse or varistor. (Not sure if it’s the issue)
Believe it was the micro switch the forward/ reverse lever actuates. I think it was stuck in the neutral position. All is good now.
Someone mentioned there's a wire on the micro switch that can break in an older thread.