81 XJ650 - Dimly Lit Oil Light

Noticed something when pulling into my garage today. My oil light was dimly lit, so dim that I didn’t even notice while riding around in the daylight.

The oil level itself seems okay. Nothing visible in the window when on the side stand, then quite full on the center stand. I’m going to check again once the bike is cooler, since reading when it’s ripping hot could make it seem falsely high.

Does this mean I have a bad connection in the electrical system somewhere? I took the low oil sensor to be a binary sort of deal: “It’s low” or “It’s not.” Is this correct?

 

Symptom update, I guess. The light is fully off when the key is turned to On, but the engine cutoff switch is off. When the engine cutoff switch is switched to Run, the light is dimly lit.

So, related to the in-gear sensor, perhaps? I don’t think my Maxim has a side stand sensor, so I don’t know why else it would have this behavior.

 

How does it look when pressing the start button - put it in gear and push start it should get bright

 

Nothing to do with the neutral switch.

The 12V positive side of the light is switched by the run switch so this makes sense.

The negative side of the light is provided by two places, the oil level switch and the starter button. It's unlikely that the light is "finding" some type of ground though the starter button or relay side of the harness so I would suspect it's finding some sort of ground through the oil level switch. You could try unplugging the oil switch from the harness (it's a pain to get to though) and see if the dim light goes away. IF it were me, I would make sure the light works when you drain the oil next time and call it a day if it does. I've learned to just make an oil check part of my pre-ride routine and not rely on lights.

 

Thank you for the suggestion. It still goes full brightness when the starter is cranking the motor, which I believe it should. I think I’ll proceed with the “check it during my next oil change” suggestion. I have checked and double checked the oil level, so I know it’s fine for now. Shouldn’t run into a problem unless I spring an oil leak mid-ride or something.

 

I have an update to this thread. Yesterday, after washing the bike, I noticed my neutral light was dimly on, but only when the engine cut-off was disengaged. Turning the cut-off to “Run” causes the neutral light to go out, but then the oil light comes on dimly. The neutral light still works correctly, turning on when the transmission is in neutral. I also did an oil change today, and I verified that the oil light still comes on when the bike is drained of oil.

Have I figured out the source of the problem? No. Have I “fixed” it? Kinda. Way back, I switched my instrument cluster lamps for LED bulbs. I wondered if maybe, the bike’s electrical system is prone to some slight voltage across those lamps that are too low to brighten an incandescent bulb. I switched the problem lamps out for the old incandescent ones, and bam, no more dim lights.

I guess the gremlin went into hibernation? I’m sure it’ll pop out at the most inconvenient time.

 

I wouldn't say its a gremlin at all, I would say its probably expected since you switched to LED's. They are highly efficient and don't require a large current to generate light, typically you don't see them as an "in circuit" indicator light for this reason.