). I was blown away that the capability was there and that they didn't do this from the factory. This is kind of in my wheelhouse as I'm an Electrical Engineering and deal with CAN bus communication all the time, although typically in the industrial world, and my day job employer is a distributor for a company that makes this type of communication cable. Since so many people were interested, I figured I would see who would like to do this that doesn't have it from the factory or hasn't already figured it out on their own. My thought is to sell the cable assembly just for enough to cover the components and a bit of my time to solder things together; about $175. I'm hoping this isn't against site rules as I'm not looking to make a profit; just want to help those like my as there seems to be a lot of interest, and it is actually incredibly simple. Once I make the cable, you plug one end in to the J1939 port on your display and plug the other end into your OBD-M diagnostic port on your engine. If you need to hook up an actual diagnostic scanner, just temporarily unplug this cable and plug in the scanner. The biggest pain is just routing the cable from the helm to the engine, but the area between the inner and outer hulls was spacious enough for me to just toss it as far as I could, then grab it from the other side, with a little contorting. Once the two are connected the display automatically sees that the J1939 data is available, and you can build your screens from tons of standard templates that are built in. You will find though that it gives you every possible bit of data, many of which our single engine bowriders do not have. So it takes some trial and error to find what is available, but everything you would expect is there; engine load, oil pressure, oil temp, battery voltage, and all kinds of other stuff.
I'm a little hesitant to help anyone with this without a little checking on your side first though. I'm not sure if Garmin has change the J1939 connector style on their unit, although I wouldn't think so as the connector on mine is the industry standard I believe. Same for the engine side; I think the flat 6 pin connector has been standard for marine diagnostics for quite a while, and I assume both Volvo and Mercury use the same one, but I am not sure.
This is the diagnostic connector you should have. It likely has a mating connector on it acting as a cover. Mine was located on the top of the engine under the plastic cowling. Here are a couple examples of the display side connection (it will at least say J1939): Let me know what you guys think!
Another neat feature that you might not know is that for $25 or so you can get an adapter that plugs into the 6 pin OBD-M connector and converts it to the standard OBDII style connector, where you can then just use your regular vehicle scanner.
