Guess i should verify what machine does and what i've done

With key off just as soon as you plug battery in to truck code -51 comes on dash display and wont go out.Truck will lift and lower(No auxillary functions tho) As soon as you turn the key on,display goes to battery state of charge and truck seems to operate normally,until you turn the key off then goes back to -51 code on display and lift/lower functions work.
Have had EV5TPS control card checked by flight systems,replaced keyswitch and steer interlock switch on the line contactor.
One thing i did find today while checking is the wiring to the key switch,both connectors have battery + voltage(36V) to them with the key off?