1991 225TXRP: how to test high temp sendor

[carboncow]

OK we just got a digital gauge wired up on our old 1991 engine...everything appears to working except the trim sender (for another post).

How would one test the high temp sender to make sure the buzzer(s) and/or gauges are working as expected. Can you short the sensor or does it work the opposite way (open).

Suggestions to test?

[rodbolt17]

turn the key on.
short pink to black.
typically on that motor the over temp icon was in the speedo.

[boscoe99]

And don't be in a hurry.

Some Yams will sound the alarm quickly. With other Yams there is a delay built in. Hold the pink wire shorted to the block (or just plug the pink wire lead into the black wire lead on the engine harness side), start the motor, and wait for a minute or so.

Can you post up a photo of the face of your gauge?

[carboncow]

And don't be in a hurry.

Some Yams will sound the alarm quickly. With other Yams there is a delay built in. Hold the pink wire shorted to the block (or just plug the pink wire lead into the black wire lead on the engine harness side), start the motor, and wait for a minute or so.

Can you post up a photo of the face of your gauge?

The tach I purchased is 6Y5-8350T-81-00 and from several sources they told me the temp warning should work...we'll see! As you can see it has the temp icon on the left.

I also understand the old buzzer warning was in the ignition and I think I see what is the buzzer...we'll be curious to test tonight as it's old and ugly looking (the ignition).

[boscoe99]

The tachometer does not contain the buzzer. It is either in a control box or on the key switch panel.

The buzzer sounds to indicate over temperature or low oil in the engine oil tank.

When the buzzer sounds you look at the tachometer to determine what is causing the buzzer to sound.

[carboncow]

That all makes sense and works for me. We'll have to determine if the buzzer works then!

If the buzzer has failed can it be replaced? it's very much part of the ignition system. Not see a part for it. I have little faith in it since every boat I've ever had has a failed horn or buzzer if exposed to elements.

[boscoe99]

Item 14 in this illustration.

2006 and Later Rigging Yamaha Outboard SWITCH PANEL 1 (SINGLE) Diagram and Parts

Item 51 in this illustration.

2006 and Later Rigging Yamaha Outboard CONTROL STANDARD SIDE 703 PULL Diagram and Parts

In a number of Yams if you try and start the motor with the kill switch activated the horn will sound. Give yours a try.

[dave1947]

Looking foe service manual

I have outboard Yamaha F115LA can not find service /parts manual

[boscoe99]

In the future start your own post and not ride on someone else's post please. Internet protocol.

Parts catalog can be found here

2006 and Later F115LA_011 Yamaha Outboard Parts

Service manual is available from Yamaha Tech Pubs, this Yamaha dealer, or any Yamaha dealer for that matter.

[carboncow]

The tachometer does not contain the buzzer. It is either in a control box or on the key switch panel.

The buzzer sounds to indicate over temperature or low oil in the engine oil tank.

When the buzzer sounds you look at the tachometer to determine what is causing the buzzer to sound.

Boscoe,

We'll things didn't go as planned...maybe you can offer some insight.

We unhooked the temp sensors from the heads and bridged the connection (with the sensors out of the equation). This didn't trigger a buzzer or the light on the new tach. I believe our buzzer is non operation as there is no sound when it starts or trying to start with kill switch off.

First I bridged the starboard head and with no trigger I then did bridged the port side...so both bridged. When I went to unhook them I noted the starboard side wires were very warm...not good!

Any idea what may be at work here? Should the sensors actually be connected and then jumper across them?

[boscoe99]

I have not a clue as to why your alarm did not sound or the tachometer did not light up.

The black wire is a ground source and the pink wire goes to the computer and to the gauge. Strange that neither of the thermoswitches worked. They are normally open. They close when they get to a certain temperature.

Your connecting the pink wire to the black wire is the same as the switch closing.

You do have a trim/oil harness connected from the motor to the gauge don't you? I thought you said that everything was working on the gauge?

"OK we just got a digital gauge wired up on our old 1991 engine...everything appears to working except the trim sender (for another post)."

[carboncow]

We worked with Andy from SIM Yamaha and are about 99% sure we got the write rigging kit and two additional connectors. Photos were taken of the connectors and he checked with Yamaha to make sure we got the right adapters.

So to answer your question we do believe we have the trim wire hooked up and the oil wire too.

Yes the gauge is working...we got oil lights, tach, light...but the trim is not working and the sender seems to be in bad shape...plus we cannot get it off (saltwater) so this may stay like this until we have time to go drastic.

This leaves us to test the warning light for high temp and we cannot trigger it.

Tomorrow I"m going to pull the warning buzzer and apply 12v to it directly and put a tester on the leads to see what happens with over temp switches bridged.

Makes you wonder if those temp sensors would engage the limp home mode, or not. Maybe there is a failure in wiring to the front or at ignition area.

Before I"m done it may just be easier to put a temp sensor and gauge in.

[rodbolt17]

a stupidly simple test.
simply unplug the stop lanyard.
crank the engine.
alarm will sound or the horn is bad.
doesn't get any easier.

[carboncow]

Thanks for clarifying that...Boscoe said that too but didn't seem 100% for all engines.

The test was preformed as you mentioned and the alarm was negative.

Since the new digital tach is showing no overheat (with a failed buzzer) when we bridge the pink/black at the switches...do you have any other suggestions?