[davepl]

FWIW, I found in another thread: "the brown/white wire you describe runs from the key switch to the firewall block on the diagrams I have. It is joined there by a solid brown wire that runs back to the cluster plug to pin 8 on the idiot light dash. It is used to feed the alternator field exciting circuit through the regulator.The ammeter dash does not have this wire."

If you had gauges, I'd makes a guess that that's why its not connected, but I don't think you do, so I'm still at a loss. Swing and miss for me I'm afraid!