The temp. switch is used only in 260Z with the automatic trans. Its function is to tell the TIU to retard the timing when the engine is cold. My temp switch's wire rotted off, and I was informed that since I lived in a mild climate I shouldn't worry about it.
The 280Z was sold only in the US. It replaced the 260Z because of the emission control. If you are in Australia, then the 260Z you have would have alot of the same parts. The 280Z was fuel injected so it could be regulated easier for emissions. Mickey