Coolant Temperature Sending Unit

Turn ignition switch to RUN position. Disconnect coolant temperature sending unit connector from coolant temperature sending unit. Touch connector to engine block. Gauge should indicate at high end of scale. When connector is not touching ground, gauge should read at low end of scale. If gauge is okay, replace sending unit. If gauge is not okay, check circuit between sending unit and gauge for an open circuit. If wiring is okay, replace gauge.