Look up the temperature sensor pin in the gauge cluster connection.
Disconnect the connection to the cluster.
Disconnect the lead from the temperature sensor.
Attach an alligator clip probe to lead from the temperature sensor.
Set your mulitimeter to continuity check.
With the other probe, touch the temperature sensor pin in the gauge cluster connection. (Is there continuity from the temp sensor to the gauge cluster?)

Also, check the ground to the gauge cluster. (I had a few wierd readings: temp gauge spiking, speed sensor error code, and turn signal lights flashing strangely. Due to a bad ground at the gauge cluster.)