Yanmar Tacho Query

[bony]

Greetings,

Would anyone on this forum have knowledge about the wiring of Yanmar Magnetic Pickup Tachometers?

I have a Yanmar 2qm15 Marine Diesel engine. It came without a Tacho when I purchased it, but I've since found a second hand Yanmar Tacho and would like to install it. However, I am really confused about the wiring involved.

Early model Yanmar Tachos ran off a magnetic pickup unit which pulsed off the teeth on the flywheel. I do have a magnetic pickup on my engine which has two terminals for wiring.

The Tacho I bought is a later model than originally supplied for 2qm15. It has an hour meter which the originals did not have, but I think it will work with my engine because my flywheel has 116 teeth and the Tacho is numbered "P116" so I assume it is the correct type for my flywheel. The Tacho has three wires protruding from the housing coloured = 1 Orange, 1 Black, and 1 Red/Blue.






My problem is that I have found three wiring diagrams (below) and they all conflict with each other as to which coloured wires go to the magnetic sending unit and ignition. One diagram is from the early 2qm15 user manual, another is for 2qm20/3qm30 engines which would have used the later model Tacho. And the third diagram is for the "B-Type Instrument Panel" which I think may have been used with this Tacho.



1. 2qm15 Wiring Diagram

2. 2qm20-3qm30 Wiring Diagram

3. B Type Instrument Panel wiring diagram


Can anyone tell me what the correct path is for each of the 3 coloured wires on my Tacho (pictured above), please?

Thanks,
bony.

[GordMay]

Greetings and welcome aboard the CF, .

Does this help? ➥ Magnetic Proximity Tachometer - Tachometer Wiring Diagram Cruisers & Sailing Photo Gallery

See also ➥ http://www.jamestowndistributors.com...hometer+Gauges

And ➥ http://faria-instruments.com/site_manuals/IS0030D.pdf

[bony]

G'day GordMay,

My apologies for taking so long to reply to your message. The interesting information you provided has shown me that there are only three wires needed to run the tacho - 1 signal wire, 1 ground wire, and 1 ignition or battery wire. On my Tacho I know that the orange wire is "signal", but I still can't determine if the black or the blue/red wire is ground. I don't want to hazard a guess and risk burning out the guts of the Tacho so I thought I might send an email to a yanmar dealer somewhere to see if I can get more information.

Thanks for your help in this matter, it is much appreciated.

Cheers,
Bony

[bony]

Well, I thought I had a Red/Blue wire but it turns out to be Red/Green (I must be going colourblind). I learned this morning that the Tacho I have is suited for a Yanmar 6LP engine so I am doubtful if it will work with my earlier 2qm15. I found a wiring diagram for the 6LP and it shows Red/Green (battery), Orange (sender), Black (ground). I'll connect it all up and give it a try, but I have my doubts.

Cheers,
Bony.

[GordMay]

Most flywheel proximity tachometers are adjustable over a range of about 90 to 180 teeth per revolution. Determine the number of teeth or notches in your engine flywheel, and set your tach’ accordingly. It should work.