Oil pressure gauge fluctuating

[Serg760]

I have a 2005 gmc sierra 1500 

with 13000 i replaced the instrument cluster with a new one new oil sensor with screen new oil and filter new alternator also. My gauge needle wont stop fluctuating from 0 to 80 psi while driving or idling  no sounds from the pump been driving the truck like this for over 4 years what can be the problem with this. Once in a while ill get the low oil pressure warning on the screen should i replace the sensor again or start with the oring or pump? Maybe the cluster is defective i still have warranty on it please help i have a new battery too

[davester]

I would suggest diagnosing the problem.

 

First, I would remove the OPS and put in a mechanical gauge, and see how much oil pressure you get and how it varies with engine speed.

At the same time, (with the OPS removed and the connector to it disconnected), see how the oil pressure gauge varies (if at all) with engine speed after the initial gauge sweep when you turn the ignition on.  If it is anything other than zero, most likely something is wrong with the OPS wiring to the ecm.