Linking twin yamaha 50s to garmin

[Tunahawaii]

I was wondering if anybody has a diagram to connect two motors to my garmin echomap 74cv so i can view fuel rate and etc. Right now i have 6y8 tachs connected inline hub to my motors, no split y’s. There are hooked up individually. From a couple of posts i read i think i need a couple multi hub connecters, main bus wire, garmin to yamaha j1939. I think i could figure it out if anyone has a diagram i could follow. Thanks in advance.

Also if anybody knows how i can get my trim to register on my tach, the motor trims up and down but doesn’t show up on my tach. Motors are brand new. check and made sure the trim sender was connected.

[fairdeal]

OK, so if,
like poster "skin diver"
you have each engine separately connected to a 6Y8 tach,
like this:




then for the Garmin to see them both,
you need to "consolidate" the Yamaha wiring,
you'll only use one of the cables that runs from transom to helm,
and replace both inline hubs with multihubs:




So you'll end up with this:

[fairdeal]

So you'll need
1 Garmin "Yamahaź Engine Bus to J1939 Adapter Cable" PART NUMBER 010-12770-00
1 Yamaha 6Y8-82521-01-00 1 ft. Pigtail Bus Wire
2 Yamaha MULTI-HUB ASSEMBLY 6Y8-81920-01-00

You'll have "left over"
4 inline hubs
and an unneeded "ORANGE MAIN BUSS WITH POWER LEAD WIRE EXTENSION 6Y8-82553-60-00"

[fairdeal]

To get the trim position to show on the tachs,
on each engine, coming off the main harness,
is a pair of pink wires with white connectors;





you'll need to take the caps off each and plug them together, like so:

[fairdeal]

Finally, to get the tachs to properly recognize the two engines
once they are on the same wiring,
you'll need to perform a reset procedure, as described in this post

https://www.yamahaoutboardparts.com/...313#post229313

[Tunahawaii]

Thank you so much!

[Tunahawaii]

I couldn’t find those two white connectors, on my motors (2021) theres a blue single wire connected to each other and yellow taped to another single black wire with a cap.5497C263-3933-464D-B9AE-522F7CE569FD.jpeg

[fairdeal]

I'm not current on 2021 motors -
but I doubt Yamaha would make a drastic change;

so I 'am confident' those pink wires are there somewhere

I 'suspect' blue jumpers are for an optional 'tilt limiter' switch

[Tunahawaii]

OK, so if,
like poster "skin diver"
you have each engine separately connected to a 6Y8 tach,
like this:




then for the Garmin to see them both,
you need to "consolidate" the Yamaha wiring,
you'll only use one of the cables that runs from transom to helm,
and replace both inline hubs with multihubs:




So you'll end up with this:

Just one more question. I have the 703 side mount controls, judging by my diagram this would mean only one control box will give power to both gauges and the multi hubs?

[fairdeal]

I have the 703 side mount controls, judging by my diagram this would mean only one control box will give power to both gauges and the multi hubs?

Yes, you only need one source of power to the hub,
(which will power both gauges)
and you can take that power from either 703's harness.

Off course if you are only running one engine,
but it's not the one you took the power from,
the other will have to be 'key on'