Oil Indicator Light Always On?

[chickenstrips]

I was told that it's normal for the oil pressure warning light to be on when the key is in the run position even with the engine off, in reference to DOHC's.

I've made sure it's not the wiring. The light only comes on if the grommet on the end of the wire is touched to a ground OR the sensor.

How can I check that I am getting good oil pressure? I have enough oil, but I do not have a pressure gauge.

OH, and a little off topic, but maybe not worth it's own thread. What size socket do I use on the spark plugs? Hah.

[Manual]

I am quite certain my '81 CB750C does not have the oil indicator light on when sitting at the run position but I can check in the a.m. As for the spark plug socket, a deep set 18mm is what works for me.

[Beekeeper]

When the key is in the on position, the oil light on my 79F is on.  Goes out almost instantly when the motor cranks, and comes back on if killed.  Is that what you are asking?

[chickenstrips]

Yes, I needed to know if it's normal to be on when off but in run position.

This presents the problem of not knowing what's causing my light while the engine is on...

Again, how could I check engine oil pressure without a gauge? With 15k miles, what are the odds that the oil pump is out? Could gas in the oil cause any of this?

[TOOLS1]

If that bike does not have enough actual oil pressure to turn the light off, it would have blown up already. You probably have a short in the wire, or the sending unit is bad. I am betting on the wire being shorted. To test, remove the wire from the sending unit. The light should go off. It it stays on then it is shorted. If the light goes out the sending unit is bad.
TOOLS

[chickenstrips]

Tools, I expected better from you. I mentioned that I tested for a short in my first post!

I get 10v from the lead when in the run position, and it turns the light on when I touch it to a ground. It also illuminates any time the bike is running, although the engine is not getting excessively hot, knocking, or otherwise going wonky.

Sending unit?

[TOOLS1]

Well at least if anyone else has this problem, they will know how to test the circuit.
Does sound like the sending unit.
TOOLS

[chickenstrips]

My question now is....is the sending unit the pressure switch?

[TOOLS1]

Yes.
TOOLS

[chickenstrips]

I started it up and the light extinguished immediately. The owner didn't understand me when I asked "is that oil light always on?"

This was the first DOHC I've worked on. Pretty nifty. I took her out for a spin and almost fell in love. First and second on this 750c really pull. Lack of kick-start, shim-on-bucket valves, ignition system, and looks are a deal breaker, though. My CL lacks everything I don't want, and that's a big deal. Haha.

The owner complained of sluggish performance and dying on idle. So the problem was resolved with a proper idle mixture, sync, boot tightening, spark cleaning and oil-change. The owner couldn't be happier. I love my work.

Here she is prior, with the oil leaks of course. The PO really believed he knew what he was doing...