oil preasure

It seems that I have an oil pressure light at low RPMs after the engine has warmed up. Its been doing this for a while; I've recently changed the oil and filter are new and I know its still there :) So I figure it could be either a failing pump or pressure switch. I would like to check the pressure with a gauge but I don't know the procedure to do this. My best guess is to screw the gauge into the oil pump pressure relief valve but I am not sure.

Second, if it happens to be a pressure switch were are they located and how are they changed. The haynes manual give the pressure measurements but doesn't outline the testing nor do they discuss the switches.

Thanks.

Unless you take a manual oil pressure test, please take my advice until you find the problem. Put a can of STP oil treatment in for safety sake. Could be a main bearing, or oil pump. Better safe tan sorry.

The pressure switch is at the "back" (toward the firewall) of the engine. Test it, and I'm fairly certain you will find your culprit.