Important safety note
is almost always a temperature sensor circuit problem, not a catastrophic motor failure. By following the diagnostic steps outlined above—starting with resistance checks and harness wiggling—you will resolve 90% of cases without replacing the drive motor. Jungheinrich Error Code 1901
He grabbed the battery disconnect, killing the power completely. This was essential. The 1901 code was "latched" in the memory. A simple key cycle wouldn't clear it; the capacitors needed to drain to reset the logic board. Important safety note is almost always a temperature