Forum:
My 94 TDS Fourtrak's thermo gauge isn't working, I don't know if it's faulty on the dash or if it is the actual thermo.. have driven it for a 200 mile round trip and it didn't move, the buggy never missed a beat either.. so any suggestions please 
Locate the temperature
Locate the temperature sender, remove the wire from the top and get someone to watch the temperature gauge. Switch on the ignition and earth the wire to a clean part of the engine, the temperature guage should rise. If it rises it is the temperature sender at fault, if not it is in the wiring or the guage itself.