So today, I set about swapping the non tach cluster plug, for the tach instrument cluster plug, along with adding the plug and correct pigtail for the center gauges. The previous owner added the gauges by tapping into the cluster plug. I kept them tapped here so I wouldn't have to unwrap the whole harness, and re-pin the junction at the fuse block. I also cleaned up the splices.
So, unwrapped tach/gauges harness:
My hacked harness and cluster:
I traced all the printed circuits and matched them up to the wire positions in the two plugs and clusters.
How they tapped into the harness at the cluster plug for the center gauges:
How to de-pin the cluster plugs. Shove a sharp pointed awl or thin/small flat blade screwdriver in like this to disengage the retaining tab for the contact.
This guy:
Center gauge harness with the lone wire that originally went to the plug. (+ power for the gauges)
Original non gauge plug removed.
Splices done.
Bend the tabs back out, and start re-pinning the cluster plug.
These two wires were cut off and taped up near the headlight switch plug. I think they were for the alternator warning light? Was that a separate feed/socked for the cluster and plug?
Anyway, I put butt connectors on to insulate them, and use them later if needed.
Also ended up with an extra terminal from the original cluster plug. Heat shrinked it and taped it out of the way.
End result:
