Mariner Mag II Oil Warning Module - bad?

[ChadMichels]

I am thinking I have a bad oil warning module on my Mariner Mag II 150hp. Serial Number 0B250842. I was trying to diagnose a constant warning tone when key was on and while running, now I have no tone at all. (No beep when key is put to run).

So far I have tested shorting the tan wire on the powerhead from the module to ground, this does cause a beep, so I know the beeper works at least. There is also what appears to be an extra wire under the dash for something, which is hooked into the system. When grounded this also causes a beep. Everything seems to be connected properly at the power head but there is a mess under the dash.

I understand there is no way to test this module other than to eliminate it from the troubleshooting list by replacing it with a known good module. I'm taking a chance on an ebay module, the prices for this module new are ridiculous, would much rather put that into a new FF.

Any other hidden tips or ways to test if this thing is working? I really need a factory service manual for this beast but Merc seems to not sell them and the prices on Ebay are stupid. The seloc wireing diagram for the V6 carb models doesn't include a wiring diagram for this module that I can find.

 

[Dukedog]

do you NOT get tha "test beeps" when key is turned on?... with key on ground tha tan coming from tha module to tha small terminal block after its disconnected from terminal block. if you get nothing or you get a solid beep module is bad............. tha module's sole purpose is to make a signal oscillate beeps.

 

[ChadMichels]

No test beeps with key on. When I ground the tan wire from the Oil warning module, I get solid beep.

I pulled the trigger on the ebay module. Will be here next week.

 

[Dukedog]

"When I ground the tan wire from the Oil warning module, I get solid beep"

is that with it separated from tha "other" tan on tha terminal block?

 

[ChadMichels]

"When I ground the tan wire from the Oil warning module, I get solid beep"

is that with it separated from tha "other" tan on tha terminal block?

Correct. Other tan is what looks like a temp probe in the port side head. I had that disconnected already as I thought that might be the cause of my constant beep.

 

[Dukedog]

alrighty then!... sounds like bad module..
gl with it

 

[ChadMichels]

Thanks Duke, you've been a big help.

 

[QBhoy]

Hi. You could test the oil alarm certainly. By manually pushing the float switch down or shorting across its wiring. But other than that. I strongly urge you do away with that oil injection system, if you haven’t already. Then link out the alarm. Amazed it’s lasted so long, if it’s still in use. Notorious for failure on that engine.

 

[ChadMichels]

Hi. You could test the oil alarm certainly. By manually pushing the float switch down or shorting across its wiring. But other than that. I strongly urge you do away with that oil injection system, if you haven’t already. Then link out the alarm. Amazed it’s lasted so long, if it’s still in use. Notorious for failure on that engine.

Yeah I did that, but I mean by checking some kind of specific voltage or resistance output on the module, which doesn't appear possible. What you are saying to do only tests the float, which works fine. Either way, still no tone from the module.

As far as removing it, the gear on the crank is in excellent shape from what I can see, and I've heard so many conflicting opinions on this injection system, I intend to keep it.

 

[QBhoy]

Yeah I did that, but I mean by checking some kind of specific voltage or resistance output on the module, which doesn't appear possible. What you are saying to do only tests the float, which works fine. Either way, still no tone from the module.

As far as removing it, the gear on the crank is in excellent shape from what I can see, and I've heard so many conflicting opinions on this injection system, I intend to keep it.

Fair play. Other engines don’t seem to suffer. But these definitely do at the drive shaft. Learned the hard way. Many others have too, for sure.

 

[ChadMichels]

I'll admit having the warning module itself die seems suspect, but I noticed that immediatly when turning the key. There is supposed to be a beep. No beep, I didn't turn the key?

What else could go wrong that I wouldnt be alerted or have forthought enough not to run the engine? There is a motion sensor that causes the beep, the low oil in gravity tank sensor that causes a beep. Seems to me any engine that dies because of this system having some kind of failure would be an operator involved issue, either from lack of maintenance or an excess of ignorance.

Don't want to come off hard headed about it, I just really don't want to have to premix fuel. There is a lot of chatter in both camps.