1995 Mariner 115 constant alarm warning, is it oil, over temperature or bad module

[itsbeal]

1995 Mariner Model #: OG176467
I?ve done a lot of research hear and other forums on this issue and found many opinions as to the cause for the alarms as well as the different fixes. I must say that all the bench tests I?ve seen baffle me as I?m no expert at the different settings on the multi meters too. Here?s what?s going on? I remember one time leaving the key on for a long time in the boat and found that the alarm under the dash started sounding. I noticed after some time that the alarm would sound off randomly without cause. It is now sounding constantly just with the key in the on position (engine off). I?ve bought a new tank, removed the old one and before putting it all back together found that there was nothing wrong with the old one, (it does the same thing as the new one). By that I mean that when the float is in the up (full) position the constant alarm is just that, Constant. When I tilt the tank upright & the float is in the down (empty) position the alarm is intermittent. Is there something with the horn itself that might be the problem? Mind you, the horn (itself) is under the dash, if that matters. I need input before I send this tank back. Also the tank number for this model is an 828362A 3 according to the parts fiche. Mercury has superseded that to a new number (892846A06 which is a back fit kit) which they claim fits my application. :noidea:

 

[Texasmark]

The alarm wire is tan or tan with a light blue stripe. The over temp sensor will be grounded when the engine water temp reaches 195F (thermostat opens at 43F) and the ground is continuous, energizing the alarm for a solid blast. If no modulation module the blue/blue-white stripe wires (2) will also send a ground to the horn in a like manner, solid blast....you have to figure out which is bad.

If a modulation module is present (as I recall) one of the blue wires (the other goes to ground) will go to the module whereby the module modulates the output to a 101010 signal....identifying the fault as low oil. From the module, the tan tan/lt blue stripe will Y into the OT wire and before going to the engine wiring harness output connector.

 

[itsbeal]

The alarm wire is tan or tan with a light blue stripe. The over temp sensor will be grounded when the engine water temp reaches 195F (thermostat opens at 43F) and the ground is continuous, energizing the alarm for a solid blast. If no modulation module the blue/blue-white stripe wires (2) will also send a ground to the horn in a like manner, solid blast....you have to figure out which is bad.

If a modulation module is present (as I recall) one of the blue wires (the other goes to ground) will go to the module whereby the module modulates the output to a 101010 signal....identifying the fault as low oil. From the module, the tan tan/lt blue stripe will Y into the OT wire and before going to the engine wiring harness output connector.

Huh? :noidea: There is a module with all the colors you speak of... but what are you saying in the last sentence?

 

[Texasmark]

The alarm sounds when ground (battery -) is applied to the tan wire in the wiring harness going to the remote control box. For that to happen, both oil and temp signals have to tie into the same wire. With the modulation module, the sense information (solid ground) from the tank comes in one pin and out another to send the 101010 ground-no ground-ground----------to the horn.....has to go to the tan wire as that is the only wire out of the engine.

The OT is already on the tan wire and is an open circuit if no OT is being experienced. Therefore somewhere in the engine wiring harness the two signals (if you will) have to merge and that is just a Y where 2 wires are wired into one. At least that's how I remember it as I no longer have my manual and it makes sense.

 

[itsbeal]

Thanks Tex for the reply. I did end up running the test that Merc calls for in the manual for the module. It tested bad which is what I replaced and that took care of the problem. So I'll be sending the wrong tank back tomorrow.

 

[Texasmark]

Thanks for the feedback. Glad you got her fixed.