temp beeper mercury 115 1991

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wahoowho?

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Sep 19, 2021
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So probably been said before but im still struggling.
Before repowering w/115 merc,i burned up my merc 100 that had temp sensor disconnected. I Repowered got new beeper with install. Worked great a long time, w/check beep each time key turned on.
So i replaced battery recently. Problem began. Stirred up my hornets nest of wiring jumble under console dash, got all working except. Right you guessed it- dang beeper!

Found and tested beeper that had only the wire going to engine connected. Tested off boat-2 wires-easy- sensor worked. Reconnected that one known wire connection. Researched and decided other wire connects to very short, hanging exsposed purple wire end coming from keyed ignition. I was optimistic. Nope, not working. Hmmm Everything at engine seemed good.
Okay how do i get this #©±¢ beeper to work?
 
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Chris1956

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overheat alarm is one wire. It grounds when it detects overheat, and grounding completes circuit sounding buzzer. Not sure what beep is.

Look on head for overheat sensor. Likely tan wire. Ground it with ign on and listen for buzzer. Most controls have buzzer built in. Some are mounted under the dashboard.
 
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wahoowho?

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Chris1956 said:
overheat alarm is one wire. It grounds when it detects overheat, and grounding completes circuit sounding buzzer. Not sure what beep is.

Look on head for overheat sensor. Likely tan wire. Ground it with ign on and listen for buzzer. Most controls have buzzer built in. Some are mounted under the dashboard.
Click to expand...


Right. Heat sensor 1 wire off head.
Beep is the sound the under console device makes each time the key passes through to start cycle to let you know its working. I realize there are horn tones/buzzing to indicate overheating or low injector oil.

As i said i locatated device, bench tested it. It worked as i attached 1 wire to positive and other to negative.

Maybe its clearer in this explanation.

One wire from buzzer goes to head .....

Where does other wire from buzzer go???
 
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Dave1027

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I have an '88 100 hp Merc which is about the same. I went though similar issues with my beeper. For me it came down to a bad warning module which I replaced. Worked fine for a while but it went bad too. After that I disconnected it and just monitor my oil level and temp gauge closely. :(
 
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wahoowho?

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Yes.
Wish mine had guage. The guage sending unit on block is present, but this ole rig been been redone on it redo?

Wonder how a guy checks that sender. If it did work at the block for temp. Id just buy a dash guage and rewire.
Thanks for responses
 
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Dave1027

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It maybe be possible to bypass the module and run the tan wire directly to the buzzer. So you'd have 12v on the hot lead of the buzzer/beeper (maybe through a resistor?) and the tan wire from the temp sender going to the ground lead of the buzzer. You could even rig a test button to apply a ground to the tan wire. I think that's how the smaller 3 cylinder versions work.
 
Dukedog

Dukedog

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"Researched and decided other wire connects to very short, hanging exsposed purple wire end coming from keyed ignition. I was optimistic. Nope, not working. "

that purple should become "hot" when key is on.. it should sound when you ground tha other wire no mater where it comes from as long as tha key is on...
 
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wahoowho?

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Right, getting closer to "solved"
Yes tan wire from head to sensor connected.
So the other side of buzser with purple lead should become hot when key is turned. We know buzzer works from bench test.
So that dangling wire , not the one to head but other purple lead @ buzzer is to be connected where? to make buzzer functional- meaning it will beep upon keyed and buzz if engine heats or gets low on oil.

Tan to head- got it.

Purple to :

A) any positive "hot" wire?
B) any ground?
C) which wire becomes hot when keyed?
D) some unknown place to me, that i will learn on this forum.

Sorry to be such a pain, but getting space to see wiring, and room to work is nearly non existant. Hence , im looking to add jump wire from dangling purple lead from buzzer to this elusive connection that becomes hot when keyed. We know buzzer works when removed and jump directly to positive and negative on a battery. So this unconnected purple wire from buzzer connects to ???
Thank you
 
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