~2005 multifunction tach wiring

[fairdeal]

seeing the recent other thread about tach wiring reminded me:

the wiring on my ~2005 multifunction tach has a feature that I have not seen in a wiring diagram (quite possible I have just overlooked it)

- a bullet connector on the trim (pink) wire



its a "two connector" tach - my F225TXRD only uses one of them
(though the original rigger used a two-connector harness)

Both tach connectors seem to have a pink wire;
I'm guessing hidden under the harness tape wrap is a "Y" splice -
one leg of which then has the bullet

Both connectors also seem to have a gray - also a Y splice on that?
I'm seeing mentioned in the other thread,
that gray on some tachs is overtemp - not so, on mine...

here's what my single connector is doing:

tach wire color to harness wire color voltage effect of grounding
green/white to green 5.15 oil light blink
green/red to green/red 5.15 temp light blinks
gray to blue/white 5.15 none seen
pink to red/white 5.5 trim reading





The way my console is constructed, I can't easily get at the back of the tach.
Can't see the wires actually coming out of the housing, can't access/see the dip switches.
Without actually removing it, I'm limited in my exploratory efforts.
I would like to see what changed if I switched the dips to 2-stroke...

[boscoe99]

here's what my single connector is doing:

tach wire harness wire voltage effect of grounding
green/white green 5.15 oil light blink
green/red green/red 5.15 temp light blinks
gray blue/white 5.15 none seen
pink red/white 5.5 trim reading

For what purpose does the esteemed gentleman from the state of Florida rise to measure voltage on a ground wire?

[boscoe99]

seeing the recent other thread about tach wiring reminded me:

the wiring on my ~2005 multifunction tach has a feature that I have not seen in a wiring diagram (quite possible I have just overlooked it)

- a bullet connector on the trim (pink) wire

I don't think many SM's from the 1990's onward depict gauge wiring.

Yamaha did at one time. Then they stopped. Why? Don't know.

[boscoe99]

[boscoe99]

I can't tell from your photos but is there an adapter harness between the trim/oil harness from the motor and your tachometer?

[fairdeal]

aha! I expected no less from you

I don't think there is any gauge wiring shown in the Service Manuals?

I was referring to the diagrams in those older 'Rigging Guide" documents that are around the internet.

While troubleshooting my trim sender,
(which led to me replacing it)
I had the meter out and was accessing the harness end anyway.

I don't think there is an adapter harness - but its in a bad place, can't examine closely.

Seems to be a single paired (2 connector) harness - you can see the one in use,
this is the other:



The remaining fascination for me is the tach gray wire -
there's the same power on as the temp and oil lights,
so it seems its "intended" to illuminate something - WIF? check engine?
except on this tach, it does nothing - the tach does not have those indicators
so why is it energized?
strange

[boscoe99]

I don't think there is any gauge wiring shown in the Service Manuals?

I was referring to the diagrams in those older 'Rigging Guide" documents that are around the internet.

The remaining fascination for me is the tach gray wire -
there's the same power on as the temp and oil lights,
so it seems its "intended" to illuminate something - WIF? check engine?
except on this tach, it does nothing - the tach does not have those indicators
so why is it energized?
strange

Stop checking for voltage on a ground wire.

On almost any device that is continuously powered, and which completes a ground to make the device function, there will be voltage seen on the ground wire from the device, when the ground wire is not connected to ground. That is what you are seeing with respect to your tachometer.

Picture an incandescent light bulb wired directly to the positive side of a battery. The switch is on the negative side. The switch is open. If you measure voltage at the bulb on the negative side you will measure battery voltage through the bulb. The voltage will be reduced given the internal resistance of the bulbs filament. That is what you are seeing.

Here is an illustration from an early SM. Wiring to the tachometer is shown. Not so in your SM.

[boscoe99]

so it seems its "intended" to illuminate something - WIF? check engine?
except on this tach, it does nothing - the tach does not have those indicators
so why is it energized?
strange

The orange wire from your tachometer is a 5 volt output wire for three wire senders.

The pink wire from your tachometer is for the trim sender input. A ground lead if you will. As the sender moves the resistance varies. The resistance changing causes current flow to change. Current flow changing changes the number of trim bars that will be seen.

The rest of the wires are ground wires. With the tachometer powered up by the key switch, if and when those wires get grounded an icon will appear or disappear on the face of the tachometer.

A check engine icon might start flashing with the grounding of a certain wire.
An over temperature icon might start flashing with the grounding of a certain wire.
A low oil pressure icon might start flashing with the grounding of a certain wire.
A main oil tank low oil quantity icon might start flashing with the grounding of a certain wire.
A remote oil tank low oil quantity icon might start flashing with the ungrounding of a certain wire.
A water in fuel icon might start flashing with the grounding of a certain wire.

Things to note:
- Yamaha changes wire colours across connectors.
- The functionality of the wires can change from the two stroke to the four stroke mode. Can, not will.
- Early tachometers offered check engine and water in fuel icons. Later models removed these features. But the wires remain. Those wires do nothing in some tachometers.

Confusing as hell isn't it? Expect nothing less from Yamaha.

Imagine a rodnut having to try and keep up with this and a million other inconsistencies that are within Yamaha outboard motors.

[fairdeal]

- The functionality of the wires can change from the two stroke to the four stroke mode. Can, not will.
- Early tachometers offered check engine and water in fuel icons. Later models removed these features. But the wires remain. Those wires do nothing in some tachometers.

too bad I I cannot access the back of the tach to check the changes with dip switch 1 and 3.

Yes, the complexity makes my head spin,
And Yamaha engineers certainly fulfill the stereotype for "inscrutable"!

to wit:
the harness wire (blue/white) which connects to the non-functional gray tach warning light wire
has a connecting wire at the engine!

I'll have to check my notes from when I traced out all the ECU pins...

[boscoe99]

This might mess with your mind. It is a photo of the tachometer leads with the blue tape removed.

[fairdeal]

This might mess with your mind. It is a photo of the tachometer leads with the blue tape removed.

Don't try to make any sense of it. You can't. It is Yamaha.

aha - exactly as I imagined it would be. Elegant.

But "why" - no, I won't go there....

[pstephens46]

I wish I hadn't read this thread.


Quick, somebody post some burnt piston pics...

[rodbolt17]

because that tach had to work with both two and three wire trim senders and two stroke carbed,two stroke EFI,two stroke HPDI and four stroke carbed and EFI motors.
two strokes used switchs for alarms.
four stroke EFI used sensors and switchs and the ECU con*****ed the alarm indicates.
yea it gets confuzzling.
then toss in I also do all the mercruiser and Volvo stuff and you wonder why I drink.

[rpambrun]

It absolutely gets confusing. I almost wish I had not read this thread too. I'm right in the middle of switching from a Suzuki engine to a 4 stroke 2005 Yamaha 225. That includes replacing the main harness, binnacle, gauges, ignition wiring and a two fuse harness for the gauges which include a multifunctional tachometer 6y5-8350T-83-00. Since it is a 2005 engine, it only has one connector on the engine, so my instructions say to put a waterproof plug in the unused female connector and plug both connectors to the tachometer on the other end.

So my question is, how does the information that comes from the engine on a 2004 engine get to the tach on a 2005 if the engine end is plugged. I've read where the ECM has changed so is the ECM putting more data on the wires in the used plug or what. I would think that the unused side of the harness, and I think it is the trim, would be null on the tach.

Do I need to be enlightened or do I just need a stiff drink?

[boscoe99]

I always choose a stiff drink over enlightenment any day. After a few stiff drinks I get very enlightened on my own. Here, hold my beer and watch this.

2005 and later F model engine to a -83-00 tachometer goes like this.