Is connecting your Suzuki outboard to a Lowrance MFD display via the Suzuki interface cable leaving you scratching your head because it's not working? You bought this nice new HDS Lowrance chartplotter, fishfinder, or MDF display and want to overlay and display your Suzuki Engine data on it but find more frustration then its worth! It seems that a lot of boaters using the Suzuki interface cable to interface with their Garmin, Lowrance, Simrad, or other products are getting intermittent connections, slow and/or lagging feedback, or readouts so inaccurate that it makes you start to think maybe your Suzuki ECU is messed up, or even your new Lowrance unit might be bad. Perhaps the Suzuki interface cable went bad?
You talk to Suzuki and they refer you to Lowrance. You talk to Lowrance and they refer you to Suzuki. You talk to a mechanic and they insist the cable went bad, but no of these avenues consider firmware / software incompatibility. What gives? Suzuki does have a good relationship with Lowrance. In fact, I believe Lowrance makes the gauges for Suzuki marine. It may seem frustrating at first but it is likely just a software issue making the the Suzuki Interface Cable not pass along the proper information from the ECU to your Lowrance, Simrad, or Garmin displays. It all starts and ends with the cable, so make that your first order of business to investigate.
In my case, I had Precision Marine in Largo install my new motor in 2016 and all rigging. I decided to forgo the Suzuki gauges in favor of overlaying the engine data on my Lowrance 12 HDS Gen 2 touch. I was able to get about 50% of the available engine data including my RPM and Temperature. I upgraded to the HDS Carbon recently and though I was able to see some data under device data, it was inaccurate, slow, lagging, and non responsive, and only showed 50% of the data. I tried everything from full resets, borrowing my friends Gen3 unit, installing my 2018 Simrad touch unit, and ended with hours of tech support between Suzuki and Lowrance with no luck. It was to a point I started looking sideways at my motor in question of the ECU output. I ran a data logger on the engine and was able to read all the data so I knew the output was fine. I then borrowed a GEN2 unit and was once again able to get RPM and Temp working as it once did. Geez...so I needed to find the cable version and noticed on the back side of my Suzuki interface cable it read software ver 2.9. A little research revealed that Suzuki states that ver2.9 is for motors from 2012 and back, while Suzuki Interface Cable 3.5 is for 2013 and newer. Hmmm!? #$^%& I was sold the wrong cable, and Precision Marine didn't catch it either. I suspected the reason for it working 50% was because the interface cable and Lowrance Gen2 were close in age, and the new carbon and Gen3 were both newer versions that were updated. I contacted the dealer in which I bought the motor from and they said it makes no difference, but was good enough to send me new 3.5 cable.
While I waited on the cable to arrive I found on Suzuki's website a software update from 2.9 to 3.5. Bingo, It'll now work with the carbon and I don't have to swap cables. I download and upgraded the software from the files menu and reset the unit to find nothing changed. Now I was really frustrated so I put it all aside while waiting. Finally, I installed the new 3.5 cable and low and behold I got full engine data overlay! Apparently the 3.5 cable is still different than a 2.9 patched upgrade cable to 3.5. The 2.9 version comes with 2 ferrite bead chokes while the new one do not. I also did an ohm check on the cable and it doesn't appear bad. I can't say 100 percent if the old cable had some unseen internal issues, or the choke design was not designed for a certain frequency it may have been introduced to in the new units, but I do know the new 3.5 cable works with no problems!
Bottom line - If you experience this issue and are running a Gen3 or newer unit, upgrade the actual cable and be done with it.