Oil pressure gauge in dash not reading any oil pressure

2004 Columbia Glider with 12.7 Detroit.
Oil pressure gauge in the dash is not showing any pressure.
Other dash gauges are working. Installed a manual test guage and the engine has very good oil pressure.
Truck runs so I know the ecm is getting a good signal.
How and wear does the dash oil gauge get is signal. I look at the ecm diagram and I don't see any interface to the dash gauges.
Appreciate knowing how the oil pressure gauge gets a signal.

 

Thanks, this one is a cluster, no separate gauge.
I need to see if I can buy just the electric motor for the oil pressure.
Thanks again