Why did my John Deere 544H suddenly stop moving, even though the shifter and fuses seem to be working?

[Frank Zimmerman]

I'm troubleshooting a John Deere 544H wheel loader that suddenly stopped moving My John Deere 544H suddenly stopped moving while loading trucks, almost like it shifted into neutral. Fuses check out fine, and the gear selector is sending voltage in neutral, forward, and reverse.

The TCU has power, but I'm only seeing about 4.9V at the transmission connector. Is that normal, or could it point to a TCU, wiring, or transmission control issue? Any ideas on what to check next?