My Oil Pressure, Coolant Temp. Gauges do not work. IVR was replaced. Fuel gauge works fine for both tanks. Pin # 14 of cluster wiring harness has a wire coming out and attached to steering support under the dash. The wiring diagram does not reflect this. Appears at one point in time it was spliced with additional wire to extend it to the ground at the steering column support.
Appears all grounds travel through the wiring harness to eventually ground at other locations. Anyone have any idea of why this ground is at Pin# 14? Am I missing something?

 

Maybe !
It would be good idea to check all the grounds you can find. Some are in the headlite area, some are on the chassis sheet metal and on and on.
The age of the vehicle has possibly allowed some of the ground connections to get rusty or have poor connections. As you know by this time what may look like a good connection doesn't have to be one. Sometimes the gauges start working after you turn an accessory on and that connection will provide a sufficient ground for the gauges to work. You could either run a new ground from the battery negative terminal to the column where all the grounds come together or keep checking and cleaning all the ground connections you can find. At this time , have no ans re- terminal pin #14. Can I ask whose diagram you are using? No all of them are as reliable as we would like.

 

Will need to check this out further, but some models used the temp gauge as the voltage source for the other gauges. Did your dash have a separate voltage regulator for the dash gauges?
Did you confirm that the wiring from the oil and temp senders was in working condition? ?
On those older gauges , if you grounded the signal wire from the sender the gauge would go all the way to full, does it?