I am pretty sure about the only thing that does not throw a code, but keeps it from moving and/or lifting is the 'hood switch' and if it is not installed and missing the jumper in the plug that it would normally be installed in plug of the wire harness. on the right side, under the hood, there should be a 2 wire plug with either a harness plugged into it for a switch that operates with moving the hood up, or a loop of wire in the plug to jumper short the circuit. I would suggest going to look at a known good machine and finding that looped wire plug and confirming that it was on your truck.
Titus is correct that the power steering function is built into the hydraulic control valve, and that if the main pump did not have output there would also be no steering but I am also pretty sure you should still get codes relating to the directional control and/or the hydraulic control circuits/sensors.