[dmjlambert]

You did catch on to what rpmerf was saying.

I think a truck with a gauge cluster just has the green wire entering the cab and going to the cluster to run the temperature gauge. The ignition switch is not involved. I just looked at the back of the ignition switch on my truck and I don't have the dark green wires going to it.

I think when they made the wiring diagram, they concentrated on the cab wiring for the warning light cluster, and only as a sort of afterthought added a pinout for the gauge cluster. They don't give us info about how the cab harness would also have some differences. You may also notice that the ammeter wires are on the engine side of the diagram but completely missing from the cab diagram, because the cab is presumed to have a warning light cluster.

So, check for continuity between the dark green wire on the cluster connector and the end of the dark green wire that you intend to connect to the temperature sender. Check that your cluster plug has the colors of the wires oriented as in the gauge cluster pinout as seen in the diagram. Then hook up your temperature sensor and see if it works.