I need some Oil Pressure Light clarification

[Guest]

I noticed something while trying to sync the carbs on my bike this evening. The Oil Pressure warning light on the bike is not going out completely. Here are a couple pictures I took to show you what I mean. Keep in mind that Objects in Picture Are Brighter Than They Appear.

Engine off:


Engine on:


Is this normal or do I have a problem?

Another reason I suspect I have an issue is that once in a while when lightly twisting the throttle, for a few revolutions of the engine I can hear the tappets tapping.

[Redman]

Meaning it was full britness when engine off (no oil pressure), and when start the engine the light goes dim but not completly off....?

Well,the light should be on or off, as operated by the oil pressure SWITCH. Is not anything in the oil pressure swtich to turn the light partly on if oil pressure a little low.

DO you know where the oil pressure swtich is..? Is on top of the trnasmisison behinnd the cylinders. Something you can do id to pull the connector off the oil pressure swtich by pulling it back (not up). THat should completly disconnect the the circuit and make the light go completly out. If it does then know is something of a problem with the swithc or is lots of oil on swtich shorting the circuit to ground. If the light doesnt go completly out, well, then know is something of a problem in the wiring or instrument panel.

Does an 81 GS400E (Conadian) have a sidestand light....? Reason I ask, is the US models, anyway, that have sidestand light, that sidestand circuit is tied to the oil pressure light circuit with a diode, and problems with that diode can cause unusall things to happen with the oil pressure light and the sidestand light.

[John Park]

Meaning it was full britness when engine off (no oil pressure), and when start the engine the light goes dim but not completly off....?

Well,the light should be on or off, as operated by the oil pressure SWITCH. Is not anything in the oil pressure swtich to turn the light partly on if oil pressure a little low.

DO you know where the oil pressure swtich is..? Is on top of the trnasmisison behinnd the cylinders. Something you can do id to pull the connector off the oil pressure swtich by pulling it back (not up). THat should completly disconnect the the circuit and make the light go completly out. If it does then know is something of a problem with the swithc or is lots of oil on swtich shorting the circuit to ground. If the light doesnt go completly out, well, then know is something of a problem in the wiring or instrument panel.

Does an 81 GS400E (Conadian) have a sidestand light....? Reason I ask, is the US models, anyway, that have sidestand light, that sidestand circuit is tied to the oil pressure light circuit with a diode, and problems with that diode can cause unusall things to happen with the oil pressure light and the sidestand light.

The oil pressure switch on a twin is in the ignition case on the clutch cover. There is a gallery that goes across to the alternator side that is capped by the cover. The gallery is downstream of the pickup, pump, filter so many things could give low pressure readings. This is a plain bearing motor designed for 40+ psi so this light should never come on when running, in my experience.

There is no sidestand interlock pre 83 that I have seen. But the switch is usually either on of off, so there may be a wiring fault that, weakly, grounds the wire and makes the light glow somewhat. The ignition part of the loom goes along the lower edge of the clutch cover in close proximity to the exhaust pipe so maybe it wasn't clipped in properly and got cooked. It has a braided cover, but that won't keep it from melting internally.

[roeme]

Also, have you made sure that the Neutral light isn't bleeding through?

[Redman]

Had not thought about the netural light shining thru somehow.
Good idea.
Try putting in gear.

If pull the wiring connector off the iol pressure stitch and light goes out, as I said before: maybe is oil and crud on the surface of the swtich that is partly completing the circuit, as I said befrore. What I didnt say is to try cleaning that off.



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The oil pressure switch on a twin is in the ignition case on the clutch cover. ...................

Ah, THanks for the correct info for the location of the oil pressure switch for a twin. (yes, my expereince has been with the 4 cylindrs)

.

[John Park]

I thought of the N light bleeding, but it doesn't seem to be affecting the high beam blue light. The good news is that the light goes off, and if there is some slight current leak it shouldn't - fingers crossed - indicate abnormal low oil pressure.

I've had a slight piston slap on these motors during the first minutes of operation during light acceleration. 450s don't seem to do it, but it's a very different piston. Five minutes and it's gone.

[Gorminrider]

if there's a "short" it'll be on the Green/yellow stripe wire, which goes from the lamp to ground through the pressure switch.

Try as Redman says and disconnect it at bullet connector (on the other end of harness from the dash, it'll be under the seat or further towards the pressure switch) . If it still glows dim instead of going out, that'll be the problem. Otherwise, the problem will be at the switch itself.

The lamps in the gauge are all in a single continuous rubber holder so unless someone has pulled this back from the gauge cluster somehow or chopped it into pieces , light should not be bleeding from neutral light on this bike.

[Polish-Jack]

Thanks for all the information and advice. I'll try to work on it this evening after work.

I'll post again with what I find out.

[Polish-Jack]

Thanks for all the information and advice. I'll try to work on it this evening after work.

I'll post again with what I find out.

I managed to borrow an oil pressure tester and the oil pressure on my bike is good enough. I found that the issue was in the instrument cluster. The rubber bulb retaining thningy was not seated properly against the white light isolating indicator tower and the light from all of the other lamps was leaking into the oil pressure indicator.

Problem solved! Thanks everyone. I'm learning from you all every step of the way.