Temperature Gauge Not Working

[migab]

Hi just bought My first celica gt4 st185 3 days ago, the previous owner said the temperature gauge worked sometimes but I haven't seen it move at all. The wire onthe temperature sender has been joined I was just wanting to Know if some 1 can tell me how to test the wire and what readings I should get.

Also can this affect the preformance as it dose feel a wee bit slow and rev's a little higher than it should (1200rpm)