1988 Yamaha 175 and new tach:

[recess]

Picked up a new(er) tach for the '88 175. According to the Yamaha manual and the Clymer manual, the tach only shows a green and black wire for reading the rpm's. My new tach, analog, not digital, yamaha tach has 3 wires, G,B, and the yellow. I know yellow is keyed hot, but is it necessary for my outboard? Or, is this tach not compatible with my motor? The oil indicator bulb wiring harness had a square type plug on it. Also, what pulse setting should I be using?

 

[rodbolt]

Re: 1988 Yamaha 175 and new tach:

12 pole or 6 pulse setting setting, yes you have to have key on 12V yellow, black is ground and green is tach send.<br /> what wire colors do you have on the engine oil alarm harness and the tach harness.<br /> what brand of tach did you get ?

 

[recess]

Re: 1988 Yamaha 175 and new tach:

I bought a Yamaha tach, brand new. Threw the box away a few weeks ago so I don't have the part number. The oil wires are b/r, g/r, y/r, and r/b. had a square plug for the connection, which I've thus changed over to yamaha style connectors. I've figured that the b/r replaces the yellow original feed wire, but the wiring diagram for the tach is what threw me. Not sure what to do with the yellow. Hook it up to the keyed yellow???? <br />Note: Hopefully will get to my place down around 5.5mp. this summer; haven't fished Oregon Inlet in 3 years. Kids keep me pretty busy up here in Va Bch.

 

[rodbolt]

Re: 1988 Yamaha 175 and new tach:

ok<br /> what wires for the alarm are on the tach, in 95 the connector harness changed from round to square, what colors are on the engine harness, if you subsitute the key on yellow you may damage the tach.<br />if the tach has the oil lights built into it it will have a 4 wire round or square plug, it should also have a blue and black for lights and a yellow for key on power and a green for tach send and a black for ground.<br />the alarm indicators are wired seperatly from the tach and lights.

 

[recess]

Re: 1988 Yamaha 175 and new tach:

Yes. Exactly as you describe. Oil lights built in. Oil wire harness has the greenish colored plug(round) at the engine. Dont have the boat here, but I remember the wires match the wiring harness on the engine. Plug fit right in and matched colors. Its the guage end of the oil wiring harness that is different. The oil lights (new tach) are a separate set of 4 wires with a square plug (b/r, g/r, y/r, r/b). I believe the oil wiring harness are g/r, y/r, g, and y. But this y runs from the Oil control unit, not keyed hot. The tach lighting wires are blue and black. The tach has green, black, and yellow wires together. It is this yellow that I am confused about, since the Yamaha manual wiring diagram does not show a yellow to the tach (other than the oil lamp wiring) for the tach for 1988. I have tested the oil lights on the tach using a battery. Positive to b/r, which leads to all 3 lamps, and negative to g/r, y/r, and r/b, lights them individually, which correlate to the "green", "yellow", and "red" indicators on the guage. I think I have the oil lights figured out, it is just the extra yellow with the tach sending wire "g" and "b" that I'm not sure whether I should hook up to keyed "hot" or not.<br />Thanks rodbolt.