Need Help Tachometer 700 DCT

[ZioFrank]

Hey all!

I tried to change my 700S dct's dashboard which is not fully sealed and steams after washing.
I bought another dashboard from 750's and connect it. My only concern was if the DCT part works in the gear selectors box...

It is working fine (except there is no ️P for the parking brake), until I noticed the rpm showing around 3.5k instead of ~1.5!
Not that the engine was idling faster, but the tachometer showing more than real rpm...!
So I tried another dashboard, same story...
I know this is because the 750cc and 700cc's are different engine, but S and X share the same dashboard, probably with different engine characteristics.
I don't understand what does it have to do with the instrument panel?! Does the speedo and tacho or fuel gauge, supposed to be informational, according to what's going on in the bike or ECU?

My question is, the info from the dashboard is sending back to ECU or it's only one way?
I mean, I can live with faulty tachometer, but will it effect the engine performance? Because according to tacho, the engine is running high, while it is not in reality...and when I rev the engine, the check engine light is coming on also...

I am confused

 

[670cc]

Hello and welcome to the forum. Posting your bike’s model year may help improve the accuracy of responses.

Absence of the parking brake indicator suggests that your new display may have been the part for a manual transmission motorcycle. Could there be different combination meter part numbers for DCT vs manual?

The service manual describes how to troubleshoot the instrument panel and it’s signals. Do you have a Honda service manual?

If the check light is coming on, you need to read the code by putting the bike in neutral, leaving the engine running, lowering the sidestand, and counting the long and shorts flashes on the MIL indicator. The resulting two digit code might suggest where the problem lies.

 

[ZioFrank]

Thanks 670 for your response.

She is from 08/2013
NC700SD RC61 abs

No, I don't have the service manual.

And yes, the dashboard is not for a DCT, but I didn't believe honda was making 2 different clocks for DCT and manual, until I saw there is no parking brake indicator...
But the "d", "s" and other DCT related stuff comes visible on it when turned on, even though it is not a DCT version, apparently!

What I don't understand is, the tachometer is 2000 higher than actual revolution, in both new dashboards (1 is with 0 kilometer and the other is used about 6000km) and as soon as I connect the original, it shows normal rpm...



Thanks in advance for helping

 

[670cc]

One thing I see in your photo is that your two displays are different versions. I can’t say for your country, but in the USA, the 2012 and 2013 X models have the odometer in the lower left corner. The display was redesigned for 2014, 2015, and among other things, the clock and the odometer swapped positions. That swap in seen in your photo, too. Perhaps along with this redesign, an internal multiplier for the tachometer count was changed. I suggest verifying that you have a new display for your correct model year motorcycle.

If your engine idles at the correct actual RPM, then the ECM is aware of the true RPM, even though it is displayed wrong, and the engine should be happy. You could also verify that the rev limiter kicks in at the correct true RPM.

 

[mtnbiker1185]

The fact this has happened between two different dashes leads me to believe that the ECM sends RPM data differently for different models. The real question is though, is the problem with the 750 vs 700, S vs X, or year differences. Which is interesting considering how Honda is known for making as many things compatible between models as possible. Me thinks it has to do with the CC size more so than anything else.

Either way, as 670cc said, the ECM knows the actual RPM and that is where all the 'decisions' are made for the engine so what the dash shows doesn't really matter. However, I would be worried that some of the other readings are off also and those might be more difficult to live with (speed, fuel level, engine warnings, etc).

 

[davidc83]

ZioFrank....you would probably need a display from a 2012/2013 model year and for a dct (the displays for manuals are different)....as 670cc mentioned...the displays were re-designed in 2014 and I also think I remember the shape of the pistons in the engine were redesigned for a slightly different shape (I will have to see if I can find that article)...from 2012/2013, valve checks were for every 8,000 miles, but with the redesign, Honda bumped valve checks up to every 16,000 miles...You are overseas and both the manual and dct versions overseas have ABS (reason why the ABS light is shown); however, if you dont have a P for parking brake...You have a display for a manual bike and not for the DCT and they really are not compatible, even though they work....Your display is getting inputs from the ECU but the inputs the ECU is sending is for a DCT display and your manual display is not showing the correct data....an analogy...You create a Microsoft Word document in Word 2016 and used special features which are in Word 2016....you try to open the Word document on a computer with only Word 2010 or maybe even 2013,,,those special features you have in your Word document will not appear, or will appear funky....nothing wrong with the document, just some incompatibility issues between how it was made and how you are attempting to use it now.

 

[ZioFrank]

Thanks for your explanations, as a matter of fact I am overseas, I lived 20 years in Toronto and now 6 years in Belgium. I can tell you a lot of differences in motor vehicle laws...
For instance, at the moment I have 6 bikes in my garage, and this NC700 automatic, is the only one I can ride legally with my license!!!

As you mentioned, this dashboard is from 750cc and my bike is 700 and like you said they have been redesigned. The ABS light turns off after first 10 or 20 meters ride, like my other bikes. The dct part also works well in the dashboard, even without P indicator.

Generally speaking, I tried to cut some corners, because I find an extremely good deal. But to my understanding it should either work or totally not. This is working well, except for the tachometer part, and if it won't hurt the engine, I will use it. Like different versions of MS word will make funky appearance, but won't effect the operating system or the computer... (thanks for the good example davidc83)

I don't think my subject is useful for others, and I really appreciate your responses, helping me a lot.
I will know more about behavior of this dashboard once I ride the bike in spring, and will update you with the results.

Good forum, good people
Thanks!