Cluster Woes

I've looked at the back of the bulkhead and there wires cut off and taped up. It maybe a previous owner has connected the wrong wire. Ill have to search for a wiring diagram.
Go to MyMopar and download the free factory manual. You may have to settle for Dodge vs Plymouth Also snare the 2 page 3rd party diagrams. These are not complete and do not show all connectors and options, but they can be easier to follow than the factory

You also might want to download the 72 manual from MyMopar. CAVEAT.....The 72 manual still has the older style "line" drawings, BUT THEY ARE DIFFERENT from 73 so you have to play "doublecheck." But they can be somewhat easier to decipher

In the 73 manual, go onwards on past the diagrams and look at the charts. Notice on the diagrams there are oval "windows" with identifying numbers. Such as "CI-2", "CE-5" whatever. The "I" is instrument panel, and the "E" is engine bay. The charts in the back then show those connectors

Here, EG from page 8-168, is the PC board connector

PCboard.jpg