Warning module testing

[smudge]

Can anyone tell me the resistance readings for the warning module on a 50hp 3 cyl 1992 Mercury?<br />I don't want to buy a new one until I am sure it's faulty. Thanks.

 

[WillyBWright]

Re: Warning module testing

They don't publish anything like that. Same for switch boxes, idle stabilizers, rev limiters, etc. It's not so easy to do simple tests with electronic gadgets. They're full of components. Other parts like sensors and coils are usually simple devices consisting of nothing more than wire windings. On those it's easy to check with common multimeters. With electronics, you'd have to disassemble the device and test each component.

 

[achris]

Re: Warning module testing

With electronics, you'd have to disassemble the device and test each component.

Or build a jig to test for every possible condition.<br /><br />Unfortunately WillyB is Wright. The easiest way to test a electronic module is to put a good one in place and see if the fault goes away; or eliminate everything around it, then replace it and see if the fault goes away<br /><br />C..................

 

[smudge]

Re: Warning module testing

Thanks for your replies. I have an electrical background and understand what you are saying. It's just that sometimes, particularly with semiconductor output devices, you can get a reading that tells you for sure that it has failed even though you wont neccessarily pick up control circuit failures. Thanks.

 

[ronmold]

Re: Warning module testing

Merc's electronics seem to have a failure problem and the oil warning module is no exception. What are the symptoms?

 

[smudge]

Re: Warning module testing

The buzzer is on all the time, I disconnected the temp sensor - no change - disconnected the oil level switch - no change, so barring a shorted wire somewhere, which is unlikely, it seems to be the module, bound to be expensive...

 

[ronmold]

Re: Warning module testing

Do you get the little oil module diagnostic "beep" when turning the key on? If not it's probably the box. Did you check the oil level switch w/ meter? I don't know if it is normally open or normally closed when reporting "full oil." Recheck if you find they need to be shorted and not disconnected. Disconnect the warning module to buzzer wire on the engine. Tan/blue I believe. If the noise stops then find some money. Parts must be spendy down under. Cheaper to scrap injection and go w/ premix.

 

[smudge]

Re: Warning module testing

No I Havent checked the switch as I do not know if it is normally open or normally closed. I was going to drain it but havent got round to that yet. Does anyone know if its N.C or N.O. (does the switch close when tank is empty)?

 

[02'Crownline]

Re: Warning module testing

i have that same problem as you do with my 92' merc 4 cyl 40. It screams everytime i turn on the key and wouldnt go off. I called my local dealer and he said its either a faulty wire, the engine was overheating, or there is an oil problem, and i know that there isnt a problem with the engine so i just cut mine... ill eventually get it repaired sooner or later...

 

[ronuncw]

Re: Warning module testing

smudge,<br /><br />I'm having the same problem on my 89 mariner 100. I disconnected and thoroughly cleaned all bullet connectors on the warning module and the terminal block (joins the temp sensor, oil level sensor and warning module). So far, its worked. As far as NC/NO, my service manual says if the oil reservoir is full, there should be no continuity....which means it's Normally Open. If continuity exists (full oil tank), then replace sensor. Oh yeah, I wouldn't disconnect the warning module if you decide to pre-mix. I think it still receives a signal from the overheat sensor (single black wire). Good Luck.

 

[smudge]

Re: Warning module testing

Hello okstfan, thanks for that I will check the switch first. If it is made when the tank is empty then a poor bullet connection will cause the buzzer to sound. The warning module does do the overheat sensor so I will not be running my motor without the warning module, have priced a new on for NZ$128.00 so its not too bad I guess.

 

[smudge]

Re: Warning module testing

Have done some more tests that may help others with this problem. When the power is turned on via the battery isolator and the ignition key turned on the buzzer will operate for a couple of seconds then stop as it should. <br /><br />Shortly afterwards (on mine) the buzzer activates again and wont go off until the battery is disconnected - this is without starting the motor and does so even with both the temp sensor and oil switch disconnected so it suggests the module is faulty. As there are no ground faults or anything like that I know the module is faulty but it would pay to get your unit tested okstfan.<br /><br />The oil switch is open when the tank is full and closes when it is empty. When the blue wires to the switch are shorted the buzzer should beep intermittently - on mine it does that 3 or 4 times them goes continuously and keeps on doing so when the contact is broken.

 

[ronmold]

Re: Warning module testing

Overheat sensor shares the tan/blu wire that goes through the harness to the buzzer, with the oil warning module but they are different circuits. The overheat does not need the oil warning module to work. If one had another different sounding buzzer mounted under the dash and a spare wire in the harness (or maybe run another wire) you could have 2 different sounds to tell you what is really happening in your motor.

 

[smudge]

Re: Warning module testing

Good point DasBoot, I did discover that but left that important bit out. Electrically the overheat sensor is direct to the buzzer. You could easily rig up another buzzer direct to the oil tank sensor, the only drawback being it would not self test when the key is turned on.

 

[ronmold]

Re: Warning module testing

Keep in mind that the oil warning module also monitors the oil pump rotation, not just the oil level. You would want to take the tan/blu send wire from a "working" oil warning module to second buzzer. A side note smudge, just ate a Fuji apple from New Zealand, best apple i've ever tasted!

 

[smudge]

Re: Warning module testing

Thanks for that DasBoot. Yeah we are pretty lucky when it comes to that stuff, but I think they send our best produce overseas.