Thanks for the reply's. The truck is 36 volt. Serial number is 5NR3636704.

what voltage is this truck?
got a serial number?
I did check both the 24v and 36v truck service manuals and HPK service documents and there is a bulletin out on this code 57.

JKPAINTER is on track with this...
is a possible issue with a auxillary circuit control.
Bulletin says it could be broken wires or an open occurs somewhere in the auxiliary hydraulic electrical circuit.
So yes, check the harness in the over the mast cable, check its connectors, especially the one at the base of the mast, it may have a cover over it but they are still prone to damage. Also check the harness in the pentograph going out to the front and make sure it hasn't been pinched.

Brewski=no book on this model but the over mast cables check with a meter 4 broken wires =on top of the carriage to the inside of compartment=if good =replace A/B valve.