Yamaha Digital Tach no Temp Indicator

fish2010

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Feb 3, 2010
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I have a Yamaha VMAX 150 with Digital Tach and Speedometer. I had some problems last summer. Buzzer going off and kicking into safety mode with the low rpm and such. I did not get a temp indicator or oil indicator. Originally I suspected and oil problem but could not find anything wrong. Today I installed a water pump kit and housing. The housing was melted. I also found one of the Thermostats was not opening. I now believe the problems I had last summer were cooling related which leads to my question. How do I troubleshoot the Temperature Indicator on the Tach and where can I find the wiring diagram to figure out if all is connected. Have never seen the Temp Indicator on the Tach since bought new in 2003.

Thanks in advance.
Fish2010
 

BaileysBoat

Senior Chief Petty Officer
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Sep 29, 2008
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Re: Yamaha Digital Tach no Temp Indicator

The Yamaha digital multifunction gauge does not indicate engine temp.

Command link gauges do.
 

gss036

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2,914
Re: Yamaha Digital Tach no Temp Indicator

The water pressure gauges are normally separate from any other instrument, I have never seen a combination gauge. Most engines. outboards anyway, do not have temp gauges, just alarms/buzzers or lights.
 

dpfundst

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Nov 28, 2005
Messages
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Re: Yamaha Digital Tach no Temp Indicator

Hi,

I have the Yamaha Digital Multi-function gauge.

It indicates the engine is "getting hot" with the bars linking, if this continues, an overheat alarm with go off...
But there isn't a reading of what the actual temperature is....

Dwight
 

rodbolt

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Sep 1, 2003
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Re: Yamaha Digital Tach no Temp Indicator

depending on the digital tach model the overtemp indicate will either be in the tach or the speedometer. its a small thermometer looking icon.
it only displays if an overheat is detected and then only if the correct oil\trim wiring harness was used.
not all digital tachs had an overheat icon, usually on those models when you hear the buzzer and the oil bar or bars are not flashing you can assume its either overheat or low battery voltage.
to test simply turn the key on,dissconect a temp switch pink wire and ground the harness side to the block, you should have an audible and a visual indicate on one of your guages.
the wire for the visual is a gray wire located in the trim\oil warning wiring harness. there is a gray wire with a bullet connector under the hood and another at either the tach or speedo.
 

rodbolt

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Re: Yamaha Digital Tach no Temp Indicator

DPfunst
reread your operators manual, the 3 bars only indicate oil level,low oil level in the remote or low oil level in the engine tank.
3 bars flashing during normal operation indicate a malfunction in the transfer system or a clogged remote oil tank filter.
so far only command link digital can give temp readings,among a lot of other things.
 

fish2010

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Feb 3, 2010
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Re: Yamaha Digital Tach no Temp Indicator

Thanks folks,
My Tach does have the temperature gauge(Thermometer Symbol), I guess it is really a overheating indicator vs a temperature gauge. I will test and try check the connections mentioned.

Does anyone have an opinion on Engine Temp Gauges, I was told you install on a head bolt. Considering this option.

thanks
Fish2010
 

fish2010

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Re: Yamaha Digital Tach no Temp Indicator

After reviewing my service manual and re reading the reply from Rodbolt it is obvious I don't understand the cooling basics.

Rodbolt can you please explain the following to me?

[Rodbolt said:] "to test simply turn the key on,dissconect a temp switch pink wire and ground the harness side to the block, you should have an audible and a visual indicate on one of your gauges."

From studying the wiring diagrams looks like the Gray Indicator wire connects to the trim sender connector and back thru the main cable to the Tach Temperature indicator.

I see the Thermo Switches and Pink wires in my diagram but what roles do the "Engine Cooling Temperature Sensor" and the "Thermo Switches" play?

Do the Thermo switches after a trigger kick the motor into saftey mode and light the indicator on the TACH? Not sure what the Cooling Temp Sensor does.

Thanks for you patience.
VR
Fish2010

the wire for the visual is a gray wire located in the trim\oil warning wiring harness. there is a gray wire with a bullet connector under the hood and another at either the tach or speedo.
 

rodbolt

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Re: Yamaha Digital Tach no Temp Indicator

now your asking engine model specific questions.
the actual engine temp sensor,if applicable, simply tells the ECU what the engine operating temp is for cold starting and a few other things but is not displayed for the operator,usually.
there again I have no idea what Vmax 150 we are disscussing.
the temp switches are just that, on or off.
the gray lead in the trim harness NOT the 10 pin main is the overheat visual indicate lead.
the temp switches simply close,taking the pink wire to ground, telling the ECU its overheated and the ECU does the rest.
a model number would help about now.
 

fish2010

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Feb 3, 2010
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Re: Yamaha Digital Tach no Temp Indicator

Thanks Rodbolt,
This actually makes sense to me now. The model is V150TLRB.

To recap the Engine Temp Sensor is for cold starting and other few things.
The Thermo Switches when they reach a certain temperature basically ground the circuit triggering the protection mode.

Taking the pink thermo switch wire to ground will simulate an overheating situation sounding the buzzer and triggering a visual via the gray wire on the trim sending unit connector. During the simulated overheating I can trouble shoot the Gray wire back to the TACH for an indicator. I assume I would have 5 volts or so at the Tach.

thanks your help is greatly appreciated.
fish2010
 
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