My oil pressure gauge has always read low in my 66 coupe. Recently, it stopped working altogether. I put a mechanical oil pressure gauge on it and the pressure was good. I then replaced the oil pressure sending unit and that did not help. I pulled the lead off of the sending unit and grounded it and the gauge moved all the way to the high side so I believe the gauge is still functional. I then checked the ohms on the sending unit while the engine was idling and it indicated approximately 34 ohms so as far as I can tell the sending unit is ok. I then pulled the instrument cluster off and checked all the wires and connections and everything seems fine. I'm at a loss. Any ideas?

 

Reading low I can understand. These "gauges" are really more of an indicator. You get used to what it normally reads then watch for changes. As for not working now, I'm not sure. You are describing a gauge that should be working. The voltage regulator on the cluster must be good because you don't mention a problem with fuel or temp gauges. Have you measured resistance of the wire from the gauge through the sender?

 

Yes I did and it measured .3 ohms. I also disconnected the lead from the oil press gauge and put it on the fuel qty gauge and it powered it just fine. The oil pressure gauge itself measured 14-15 ohms across which I heard is low. I'm thinking of spending the $$ for a new gauge because I'm not sure what else to try.