this is directly from haynes chapter 3 page 6 . " if the gauge indicates hot shortly after the engine is started from cold, disconnect the coolant temperature sender's electrical connector. if the gauge reading drops replace the sender. if the reading remains high, the wire to the gauge may be shorted to ground or the gauge is falty.
if the gauge fails to indicare after the engine has been warmed up(about 10 minutes)and the fuses are sound, stwich off engin,dissconnect the senders ellecrtical connector and use a jumper wire to connect the red/white wire to a cleen grounding point on the engin. stwich the ignition to on with out starting it. if the gauadge is now hot replace t he sender.
if the gauge still doesent work the circuit may be open or the gauge may be faulty"
