Flickering oil warning light

[EvelKeevil]

I have a flickering oil warning light on my '79 SF. It only happens irregularly. The bike has lots of oil in it, has good compression and generally runs very nicely. It happens sporadically when the bike is hot and I'm rolling off and braking for a corner. I thought it might be an electrical glitch but can't find anything obvious. The bike stood for many years before I bought it and I've restored it. It has only done 22,000 miles from new and I'm only the third owner. I don't think there is a mechanical problem but it is working on my nerves. Any advice gratefully received!

[DEEBS11]

Evel, this is how the circuit works. 12 volts positive on bulb at all times. The oil pressure switch completes the circuit by grounding when it does not have sufficient pressure to hold the switch in the "open" position. Pressure on/light out. The first easy thing to try would be to replace the switch because it's the most complicated device in the circuit and most likely to fail. A lot of these fail open but most people do not notice because the light never comes on even when it is supposed to (cold start key on before you hit the start button).

[DEEBS11]

The part

https://www.ebay.com/itm/20173399999...Cclp%3A2047675

[bikerphil]

You know on only the 79 Special, the oil warning light doubles as a warning for a burnt out tail running light. It is controlled by a light checker unit under the left plastic side cover. The terminals in the connector plug become loose/corroded and will cause the flickering warning light. Try jiggling the connector and see if the light goes off. Here is what the unit looks like....

[DEEBS11]

Interesting reading Phil. A one year only circuit.

https://xs11.club/forum/idle-talk-fo...-warning-light

[EvelKeevil]

Thanks everybody. I have replaced the switch, so that's not the issue. I've checked the tail light and that's not the issue either. The warning light only flickers occasionally. It isn't static. It's not on constantly and when it does come on it just flickers for a second or two and then goes off again. I've changed the oil and filter three times in 1000 miles and it comes out nice and clean. I guess maybe I should drop the sump and check the gauze filter isn't silted up. Otherwise all I can think of is that it must be an electrical problem due to the sporadic nature of it. It is worrying me though.

[DEEBS11]

I think Phil is right about finding the module and unplugging it and cleaning it up a bit before you plug it back in. That is where the issue is more than likely.

[bikerphil]

Yep, the pin and socket type connectors get flaky, the sockets can stretch open a bit, they can be closed up a little with a tiny jewelers screwdriver.

Every time someone posts with this type of problem, the bike is always seems to be a 79SF.

[Radioguylogs]

I had the same problem on my XS750SF, which has the same design. My problem turned out to be a dirty connector under the gas tank.

[canuckroy]

I just found a connector problem on my 79 xs1100 under the left side cover in the LCU unit. I sprayed the contacts with ignition cleaner then WD40 and my taillight now works, and the oil light is off on the dash. Thanks for the helpful tips. This is great forum. I'm restoring the bike after it sat in a sea can since 1992.

[bikerphil]

Glad you got it sorted out 🙂.

[EvelKeevil]

Just to revisit this, I went through just about every electrical connector I could find, cleaned them all up and sprayed them and the problem now seems to have gone away. Fingers crossed! Thank you for all your assistance.