Yamaha analogue tachometer wiring

chirombo

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I have a old style Yamaha outboard tach I bought recently and need help with the wiring. I've searched my manual and the net without much success.

On the back of the gauge are 4 terminal posts labelled 12,B,6 and G.

12 is unconnected

2 black wires connect to B, one is cut (I assume it runs off to supplementary gauges and is unnecessary?) There is a terminal bridge from B to 6. I think this is for 6 pole, which I assume to be correct for a 60hp (6H2 60FEO), as normally is for 40 to 70hp.

2 green wires connect to G, one has a female connection and I've assumed it's supplemental, as above.

1 yellow, 1 green and 1 black come from the tacho in a loom that connects to the yellow, green and black loom hanging off the back of the Yamaha 703 remotes.

However I also have a yellow wire with a 10A inline fuse, that has been cut at the tacho end. I assume this is the ignition feed, but cannot find a wiring diagram that shows me where it goes, or to what terminal it attaches on the tacho?
 
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boscoe99

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Re: Yamaha analogue tachometer wiring

Does the tachometer have warning lights or not?
 

chirombo

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Re: Yamaha analogue tachometer wiring

Does the tachometer have warning lights or not?

Nope, no warning lights - a completely vanilla single needle, no-frills version from Nippon Seiki with max RPM to 7K.
 

boscoe99

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Re: Yamaha analogue tachometer wiring

Yellow is for 12 volt positive, black is for the ground and green is for the tachometer signal. Hook those three wires up and see what happens.

I think you are correct about the number of poles in your motor. Sounds like the tachometer is already configured for a six pole motor.

The three wires from the tachometer normally connect to a small fused harness that runs to the 703 control box. The control box of course gets its electrical power from the motor.
 

chirombo

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Re: Yamaha analogue tachometer wiring

Yellow is for 12 volt positive, black is for the ground and green is for the tachometer signal. Hook those three wires up and see what happens.

I think you are correct about the number of poles in your motor. Sounds like the tachometer is already configured for a six pole motor.

The three wires from the tachometer normally connect to a small fused harness that runs to the 703 control box. The control box of course gets its electrical power from the motor.

Am being thick here, does the yellow ignition feed wire hook up to '12'? Black and green are pre-wired, but yellow is cut just short of the tach and close to the in-line fuse. The remotes side of the harness is intact with it's plugs.

I don't want to risk cooking the gauge, as the alternative digital version is the equivalent to a decent stainless prop in cost.
 

boscoe99

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Re: Yamaha analogue tachometer wiring

No, don't believe the yellow wire goes to the post marked as 12. I think the jumper bar is connected between the #12 post and the middle post if a 12 pole tachometer is used.

In all Yamahas, yellow is for key on power. That means when the key is turned to the on position the yellow wires, wherever they may be, get positive battery power.

I thought you indicated there is a separate yellow wire coming from the tachometer? This should be for positive power.

"1 yellow, 1 green and 1 black come from the tacho in a loom"

I understand that later version digital multifunction Yam tachometers can be found on the internet all day long for about a hundred bucks.
 

chirombo

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Re: Yamaha analogue tachometer wiring

Apologies, am just confusing you (and myself)!

The loom from the tachometer to the remotes has at it's 703 remote side, the yellow, black and green wires that plug into the short matching loom that hangs from the 703. At the tach end, black (B + 6 pole) and green (G) are attached to their terminals, but yellow fuse end has been cut short...it's that one that I've no clue as to where it connects?

The reason I went with this was I'm running 'modern' power on a 1960ish boat and this was the closest I could get to the look of the original '60s Aqua Meter tacho. On our side of the pond the used digital versions are still serious money.
 
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boscoe99

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Re: Yamaha analogue tachometer wiring

Looking at this some more (particularly the photo in the link provided) it appears there is a terminal for the green wire and a terminal for the black wire. With the black wire terminal being jumpered to an unused terminal (#6 in in this case) that is not powered. Therefore, apply the yellow power wire to the terminal marked with #12.
 
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