Gas gauge works, and the voltage limiter in the gauge tests OK. I have juice to the wire going to the sending unit and the sending unit is new. The temp guage will not move. Tried two spare temp gauges I have and they don't move the needle either. I wonder of the curcuit board has a bad conection somewhere. Any ideas?

 

I'm not familiar with the physical layout of the panel for these cars, but it should be easy to run down. You'll have to "lay out" the dash, and you can actually do some of this with the cluster clear out, and just hook the thing up to a battery, or maybe just do some continuity checks

The nuts connecting the gauge terminals to the PC board are suspect, loosen/ tighten the nuts, or remove/ dissasemble the unit and clean the copper and replace the nuts.

On my Dart, the temp and fuel gauge are actually on separate boards, so the harness must jumper the gauge power between the two boards

Some of the problems are

Pins for the connectors on the boards become loose/ corroded, you must solder the pins to the boards. On my car, I did away with the original connectors, and went down to Radio Sh$$ and got 2 sets of "Molex" style connectors

(Not in this case) The instrument limiter "socket" on some cars is brass springy fingers pressed into slots on the board. These need to be soldered to the board copper as they lose contact.

The fore-mentioned nuts/ studs at the gauges lose connection at the board.

Obviously they must have continuity through the wiring to the senders