If this unit has a Curtis PMC (code 31) there is a problem with communication between the control handle (tiller handle) card and the PMC controller. The cable might be damaged? or the Tiller handle card might be bad( these are known to go bad ), don't have much problem with the PMC. If the cable is good and you want to change the tiller card be sure to ask for the Service Gram that goes along with it for programing. Curtis makes a handset for testing and programing the units, comes in very handy cost about $500.00.