you have hydraulic function and that is good you dont need to short BDI because BDI turns off total hydraulic when is battery low,to save power in battery till you go on charger.Your problem with slow hydraulic is somewhere in wiring potentiometer for first function or electronic unit and you look that part of truck.I was look this vehicle and on BDI pin 3 is for hydraulic if you still want to try.Good luck
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