2001 Yamaha 50 TLRZ 2-Stroke Low Oil Warning Buzzer

[TGriffin]

Here's the skinny...The boat sat for about a year and all was fine prior. When I got around to getting it ready for use I found the fuel filter had started leaking. That required removal of the oil tank. I added a fresh fuel pump and filter and re-assembled everything. Upon turning the switch on I am getting a constant warning buzzer. The manual I have is not from Yamaha but did give specific procedure for testing continuity on the oil level sensor...The sensor failed at the low oil position. Manual said replace if failed so I ordered in a new oil tank level sensor and installed it. I'll add the warning buzzer doesn't sound with the oil level sensor disconnected. It also puts the engine in limp mode when the buzzer is sounding and I haven't attempted starting with the oil tank unplugged. Got the new sensor installed and get an immediate warning buzzer when turning the key. I pull the new sensor and it also fails the test at the low oil level. Frustrated I gave the new sensor a few light taps on the edge of the table in case it was sticking. At that point it failed continuity at full and empty. I got a refund on the switch. Bottom line both switches failed at the low oil level. I've got another to be here next week.The manual clearly shows the switch I have and states the switch must be replaced if there is no continuity at the low oil level...What's the possibility my switch went bad sitting and I got a defective switch to replace it??? With the new switch losing continuity at the full mark from a few taps against the table I'm taking it they're quiet sensitive. I've not traced the green/red stripe wire to the control box looking for a short to ground nor have I tested it for voltage. With the failed continuity test I was going with that but I'm questioning it...Any help will be greatly appreciated.......

[TGriffin]

Finally getting back to working on the boat. New oil level sensor arrived and it passed all continuity tests. It's installed and I'm still getting the low oil warning buzzer. The buzzer goes away with the oil level sensor unplugged. Two things can set the buzzer. Overheat and low oil. The overheat sensor tests for continuity and the buzzer is still present when it's unplugged. My only option at this point is the control module but I really don't suspect it and I'd just be throwing parts at it at that point. Anybody ???

[99yam40]

I would think the over heat switch should be open when not alarming, this sounds opposite from what you said.
are you sure you know how to test these things?

[TGriffin]

It has been a couple of weeks since I tested the overheat switch for continuity. I'm pretty sure it was to have no continuity. At any rate it passed the test per the manual. The overheat switch also had no effect on the buzzer while the oil level switch does. I'm testing according to the manual.

[99yam40]

It has been a couple of weeks since I tested the overheat switch for continuity. I'm pretty sure it was to have no continuity. At any rate it passed the test per the manual. The overheat switch also had no effect on the buzzer while the oil level switch does. I'm testing according to the manual.

sounds like you say it has continuity even tho it should not have it.

but it does sound like the oil level or wiring is a problem

[TGriffin]

All tests performed per the manual. The original oil level switch failed continuity at the empty level. Manual says replace at that point. The replacement switch was installed without testing and set the buzzer. Pulled and tested the new replacement failed again at the empty level. A couple of light taps on the switch and it then failed at full and empty. Third replacement switch passed all continuity tests at the parts counter. Was installed without further testing and set the buzzer. It's still installed at this point. The whole thing is pretty cut and dry...1 ground that has been tested and 2 plugs on the switch. Function of the float was tested after the screen was cleaned and installed.

Like I said it's been a couple of weeks since I tested the overheat switch. Pretty sure it was to be open/no continuity and it passed that test. Given that overheat and oil level are the only two things monitored by the buzzer and the buzzer goes away when the oil switch is unplugged I believe I'm on the right track. Unplugging the overheat switch has no effect on the buzzer and again it passed the continuity test.

The pink wire from the oil switch goes to the control module. It sets the limp mode and is operational. Due to the buzzer going away I'm going to assume the module is operational and will test to see if unplugging the switch will also cause the limp mode to go away.

At this point I'm gonna dig into the electrical schematics and see if I can test to see if the switch is getting proper voltage.

[99yam40]

it is my thinking that when the pink wire is grounded by either the over heat or the low oil switch the alarm sounds and motor goes into RPM limit.
So both switches should be open until a problem shows up and then they ground the pink wire .
so no continuity in normal, but continuity when oil level is low and when over heat happens

[ausnoelm]

I am dizzy trying to follow your trouble shooting, but, I will say, almost all oil alarm faults are wiring related, it needs to be remembered, the ground is switched, not the positive side.