1989 Honda FL400R Pilot Service Manual, Page 53Get this manual
COOLING SYSTEM
TROUBlESHOOTI NG
Engine temperature too high Faulty radiator cap Insufficient coolant or coolant level too low Passages blocked in radiator, hoses, or water jacket Cooling fan motor does not turn Faulty fan motorFaulty thermostatic switchPoor contact or open circuit in harness Faulty water pump Air bubbles in cooling system Engine temperature too low Cooling fan motor does not stop runningFaulty thermostatic switchshort cifcuit between the fan motor and thermostatic switch