relay has 4 wires in total.
2 = coil
2 = bridge
coil 1 = ignition switch positive with diode to prevent backwash (engine afterrun)
coil 2 = thermosensor wire 1
bridge 1 = from fused battery connection
bridge 2 = to radiator fan relay positive.
connect the remaining thermosensor wire to any good ground, ensure the radiator fan earth/ground wire is very good and solid connection.