Measuring the actual oil pressure on a 3.1 Pontiac TS SE

Unfortunately my Pontiac Trans Sport SE doesn't have a real oil pressure gauge. It's more like an on/off switch and shows the same value no matter what oil pressure I have. It's designed to drop only if you have a serious oil pressure issue like zero pressure at idle...

Does anyone know how we can measure the real oil pressure for this engine?

The best thing would be if I could find a sensor/setup that would report the real oil pressure on the dash gauge...

I think you will need to remove your oil pressure sending unit and put one in that will be compatible with a pressure gauge. I did a quick search and found this on the internet.

http://www.glowshift.com/instructions/7-Color-Series/GS-704-Oil-Pressure-Gauge.pdf

Look a the diagram here: it shows the difference between the 3.8 setup (VIN L real pressure) and 3.1 (VIN D switch)
www.avigex.ca/xport/instrumentpanel1.jpg
By replacing the 3.1 switch with the 3.8 sensor, you would use the same gauge on the instrument panel and it would show proportional .
http://www.avigex.ca/xport/oilswitch31.jpg has 3 contacts
http://www.avigex.ca/xport/oilpressuregauge.jpg has four contacts
available at rockauto.com under
pontiac/1993/transport/3.8/ electrical switch and relays/oil pressure switch

Notice both the 3.1 pressure switch and 3.8 pressure analog sensor also contain a second contact set C and D to keep the fuel pump running. I think they use the same connector.

http://www.avigex.ca/xport/fuelinjection.jpg for 3.8
http://www.avigex.ca/xport/fuelcontrol31.jpg for 3.1

Thank you LMP and rkvons for the documented answers!

I will order the oil pressure sensor from the 3.8 and see how it shows on the dash gauge (the connectors look the same but the part no. is different from the ones shown by rockauto in the 3.1 Vin D section).

YOu will have to remove or disconmnect the 68 ohm resistor to ground that is wired in the VIN D circuitry. It it said to be located in the engine wiring harness approx 15 cm from C100 contact breakout. THis is a 10 contact connector mounted near or to left hand hood hinge.

Thank you LMP! There are some oil pressure sensors listed in the rockauto catalog in the oil pressure switch category for the 3.1 Vin D TS.

I'm ordering one and get back with the results :)