Temp Gauge Test

[wraprail]

I think you are correct. You can trace the gauge circut on the back of the cluster to make sure which is ground, positive and sensor. If you ground the sensor wire on the engine and the gauge did nothing then you ground the same location on the gauge with a jumper and the needle moves I would assume the trouble is in the wiring. Could be in the printed circut on the back of the cluster. Could be the actual wire going to the cluster. Could be the connectors that the gauge mounts to. Those are the first places I would check..