I replaced my temperature sensor because the spade connector broke off and the gauge wasn't working.  Now, the gauge goes to the halfway point before it even warms up and then moves up slightly after it is warm.  I replaced it with Duralast part number TU89 from autozone, which is what their system says is the part number.

What is wrong?
Did I get the wrong sending unit?

I wouldcheck all the wiring, make sure it correct, I think there is only two wires. Mine goes up to normal range and when I hit the gas it goes back down,I have to wiggle the spades every now and then to get itto work.how much was the auto zone unit?I wouldcheck out suzuki,

The temperature switch on mine only has one wire and is at the front of the thermostat housing.  The part was $13.99 at Autozone.

I will check mine tonight, and update

You can test the sender with an ohm meter. It should slowly change as the vehicle warms up.

Check your water level.  I had a similar issue when I had a leaking heater hose.  I would get an air bubble in the cooling system and the temp sensor would show the wrong reading for a while the suddenly kick in.

did you get it tight?  did you use goop or teflon tape?  The sender works as a variable resister to ground.  if it has bad ground, it will be innaccurate.  i would check that first.

My 97 tracker had the spade loose on the temp sensor. I soldered it on and it has worked great since.