Using CaseIH magnum 305 with autopilot system. Tractor is factory guidance ready, we are using a fm750 display, NAV II. System has worked great for years. This year went to the field and unable to engage guidance. Brings up a fault 042 and says low voltage. Have cleared the fault and comes right back. looking for any troublshooting advice on this fault , as there is not a lot of info found for trimble autopilot fault 042.