2001 S40 with an oil pressure light

[bgairborne]

Hello everyone:

I have an oil pressure warning light on on my dash, but I'm not convinced the car has low oil pressure. The car runs great and doesn't seem like its running dry (ie. no loud valves, hot smells etc.) I disconnected the wire to the oil pressure sensor and the dash light stays on. This circuit seems like a simple one, but I'm wondering if I might be missing something. Since the switch grounds the circuit to the engine block and triggers the dash light when there is no pressure, shouldn't unplugging the switch, thus keeping the circuit open, make the dash light go out? What am I missing? Looking at the wiring diagram, I see the single wire from the sensor goes to the ECU. Could it be a faulty ECU that is somehow constantly grounding the oil pressure circuit?

Finally, I put the sensor back in the engine and attached one end of an ohm meter to the sensor and the other to the block. I get conductivity when the engine is off, but the switch opens when I run the engine, implying that I do indeed have oil pressure. What am I missing?

As well, plugging a diagnostic tool into the car I get a long list of codes:

ecm99 Cylinder misfire
ecm82 a/c cooling fan
ecm78 RPM sensor
ecm5d Camshaft reset valve
ecm7d a/c system
ecm2e boost pressure
ecm16 oxy sensor
ecm3a ignition coil #2
srs50085 driver's side SIPS

But I'm thinking that if these were real problems, the car would run rough, and it doesn't at all. Thanks in advance for you thoughts!

Brian