I think I'm going to install a real oil pressure gauge in my truck. Where does the stock glorified pressure switch look at pressure, before or after the filter? It probably doesn't make a big difference, but I would rather compare apples to apples. Thanks, guys!

 

i used the port on top of the oil filter housing

 

Thanks, but that's not quite what I was asking. Anyone else?

 

there is no way to compare the factory gauge gets a signal from the ecm to show what the pressure should be at that engine temp and load on the motor.The sensor giving the ecm the signal will read 7 psi of pressure and your gauge will show 40 psi. anything below that is when the cel will come on

 

I believe it's after the filter.