Hi 2pac, we have 2 kone crane's here.
You say you pass current through the sensors (which I assume are current transformers), is this current ac or dc, some ct's can work with either, but some are ac only, plus the amount of current your using might be too low.
I have a couple of Abb current transformers which are active, and can measure ac and dc, they work by balancing out the magnetic field in the core, and the control voltage that does this is the current output signal.
Speaking of output signal, this may be a current signal, if this is the case the output needs a load resistor, if you remove the sensor from the circuit you'll just get full +vcc or gnd outputtted.
The other thing is the controller itself may well have eeprom and the fault may not be reset without a laptop and software, or a secret manufacts 'trick', more and more stuff is like this these days.
Unusual to see 3 ct's, usually drives just use 2, the third phase is assumed to be the same as the other 2, maybe being a lifting machine theres a safety reason for it.