That damned oil light...

[nwforester]

Just wondering if someone could help me clear up a rather annoying problem. I've got a 79SF, 30K miles. The oil light is basically always on. It's off for about 100 miles (sometimes less) after each oil change, but then comes on and pretty much stays on until the next change. Usually it coincides with a high rev. I've ridden it like this for 3000 miles with no engine noise or problems, however. At least I don't think there have been any. The transmission makes one hell of a 'clunk' on each shift.

I've read several posts on the subject and can't seem to isolate the problem. Here's what I can say after research and digging into the bike:

1. The order of the spring, washer and filter on the oil filter bolt. I have no idea what this is all about. Can someone elaborate? What is the proper order? What washer? How would this affect oil pressure?

2. Taillight wiring. A previous owner wired the tail light straight to the fuse box. The blue wire in the tail assembly which runs to the light checker is not in use at all. I messed about with the light checker unit and the light went off, but then came back on within an hour or so. But seeing as how the light goes on and off with oil change, this rather complicates things.....

3. The manual shows a tan wire into the light checker circuit at the fuse panel, but there are several tan wires. How am I to know which one?

Help. For now I've pulled the warning light bulb. But that kinda thing just doesn't sit well in my head.

Thanks to all who respond,

nwforester

[Jerry]

Had a similar problem on an XS 400. Turned out the top of the pressure switch had picked up a film of oil and dirt, enough so that the 2 contacts on the top of the switch were shorting out, causing the light to come on. A shot of of carb cleaner fixed it right up. Humidity level seemed to be the final straw; humid = light on, dry = light off. Drove me nuts for a while.

[nwforester]

Thanks, Jerry. I'll give that a try. Hopefully I can yank that little bastard without taking off the fuel tank and/or carbs.

I should also mention that the wire to the sensor is not touching any other piece of metal. Everything looks kosher there.

[bikerphil]

The light checker unit (warning device for burnt out bulbs) on my 79 Special would illuminate the oil light, causing me to think no oil pressure, even though all the bulbs were good. I ended up twisting the wires around where they go into the light checker module, and the oil light went off. Try twisting those wires down there and maybe you'll get lucky like I did. I twisted the whole unit about two times around and mounted it back on the bike and it's been fine ever since. In case you haven't, check all your bulbs. HTH

[79XS11F]

Just wondering if someone could help me clear up a rather annoying problem. I've got a 79SF, 30K miles. The oil light is basically always on. It's off for about 100 miles (sometimes less) after each oil change, but then comes on and pretty much stays on until the next change. Usually it coincides with a high rev. I've ridden it like this for 3000 miles with no engine noise or problems, however. At least I don't think there have been any. The transmission makes one hell of a 'clunk' on each shift.

I've read several posts on the subject and can't seem to isolate the problem. Here's what I can say after research and digging into the bike:

1. The order of the spring, washer and filter on the oil filter bolt. I have no idea what this is all about. Can someone elaborate? What is the proper order? What washer? How would this affect oil pressure?

2. Taillight wiring. A previous owner wired the tail light straight to the fuse box. The blue wire in the tail assembly which runs to the light checker is not in use at all. I messed about with the light checker unit and the light went off, but then came back on within an hour or so. But seeing as how the light goes on and off with oil change, this rather complicates things.....

3. The manual shows a tan wire into the light checker circuit at the fuse panel, but there are several tan wires. How am I to know which one?

Help. For now I've pulled the warning light bulb. But that kinda thing just doesn't sit well in my head.

Thanks to all who respond,

nwforester

Oil filter setup is the hollow bolt up through the bottom with a new O-ring on it, drop the spring on the hollow both from what would be the inside of the filter bowl followed by the washer and then the filter. The order affects the flow of oil because the filter needs to be at the top inside the bowl. Don't forget to use a new lightly oiled O-ring in the grove around the top of the oil filter bowl.
Your instrument pod lights should hook up with a block connector in the headlight bucket. As was suggested do confirm that the wiring is in good shape and the block connector is clean and fits tightly together.
If you have a manual there is a method for testing the oil pressure sending unit. Clean it first as was suggested
Rob

[Jerry]

here is part of the microfiche diagram that shows the order of components in the XS - XJ 11 oil filter:



Filter
Washer
Spring

[Ivan]

Correct me if I am wrong, but I dont think the oil filter would have much affect on oil pressure as long as the bolt its self is inplace. The bolt has the bypass spring in it, so you could put it all back together with no filter and get pressure.

The pressure switch is after the filter anyway. Its where the oil travels from the case to the head, so the only thing that would affect the light would be in the the head. Unless there is so much clearance in the bottom end that there isnt enough oil to fill the passages in the head.

If you dont find any wiring problems (which I would rectify first anyway) it would be advisable to pull the valve cover and look into the clearances on the cam caps. I would check this especially if you have any inkling that there may have been gas in the oil.

To test the switch, just take the terminal off and hook your 12V test light to power (NOT ground) and touch the switch terminal with the tip. without the engine running, it should light. when running, it should go out. (unless the switch is a normally closed switch, then it will be opposite. I cant imagine this being the case.) Pressure switches are pretty universal, as long as you find one with the right thread and one terminal, it should work. They typically switch at 4-10 psi, so most anything should work. The one on my scoot looks just like the ones Ford and Chevy used to use, which were dirt cheap. I'll bet Yamaha thinks they are made from gold....

[DGXSER]

I know that my oil filter did not have the washer in it when I pulled it for my first oil change, the spring was actually inside the oil filter. The oil light almost always lights soon as you turn the key and will light after just bumping the starter if it was not lit. It always has and does go out soon as the engine starts. So the filter not being "lifted" into position did not cause my bike to lose oil pressure.

[Dragon Tamer]

If your tail light is not wired into the "light checker" it will read that as a fault and light the light. I had been plaqued by the same scenario for several years and finally just removed the wire from the pressure switch and insulated it. Then I removed the switch and installed a tubing adaptor and the tubing to an oil pressure gauge, now when the light comes on (which it still does now and again) I just double check that the gauge is reading pressure and ignore the light. Yup, been raining for a couple of days and the light is lit alright, humidity gets into something and at least in this case it is not the switch, cause it is in a drawer somewhere in the shop.

[John]

Ivan

The oil pressure switch is NC, and probably opens at 5 psi to turn off the oil light, If it were NO, then the light would come on when oil pressure hit 5 psi. All the switch does is provide ground for the circuit.