The botXXXXX XXXXX wire, last one in the row goes to the temp sender, you can trace the wires, from the gage, etc. The black is the common ground. If you put a test light or volt meter on the back terminals of the gage, you should get a 12 volt reading on the power side, the temp sender side will be either real bright or real dim, you can unhook the sending unit and watch for the change at the terminals on the gage. Open circuit at the sender should give a higher voltage reading at the gage, etc. If you have the cluster out, you can trace each segment of the printed circuit board, just by following it and then comparing it to the plug in connector. Sorry, I don't remember which way the resistor connects or if that unit even used one, if so it will be a small white resistor that connects across 2 of the terminals on the gage. Sorry, I also do not remember the resistance. I do remember that on the early S10's there was one major ground, black wire, that connects to the lower left side of the dash pad at one of the metal brackets close to the park brake release lever on the bottom of the dash pad. But, again, don't remember what year they moved it or where too. Memory is fading fast, sorry. Can only hope some of this helps you, been too long since I had one apart, but would remember quick if I had it here to look at. If I come up with anything else, I will be happy to send it to you. It may even be that they only used 2 of the terminals and used the sending unit for the only ground on it. The change in ground resistance being what changes how the gage reads. Thanks and good luck
Found the other half of the dash diagram, maybe this will help some more.