the fc4000 does not use a steer position sensor
the brake pedal switch will reduce speed
the mast staging switch will reduce speed
i suspect your brake switch
if your truck works in water the left front wheel sprays water into the distribution board located under left step
when the board corodes you get many strange faults
try placing blocks under mast so both drive wheels are off of ground, drive unit and observe drive wheels
when releasing accelerator pedal observe if both wheels stop suddenly or if speed winds down
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.