| Author | Message | ||
     Greg_e |
Does anyone know how the speedometer on an 03 XB9R works? Does it take a signal from the ECM or does it make the computations from the wheel sensor inside the gauge? I'm thinking of putting in a completely different fuel system and of course need to keep the speedo so I need to figure out what is going on with how it works. I'll assume that the tach. works by just getting a pulse from the ECM and most of the alternate fuel systems can send a variety of signals to a tach. (Message edited by Greg_E on October 05, 2009) | ||
| Blake |
Speed sensor is a Hall-Effect sensor mounted atop engine case on right side at tranny output shaft. | ||
| Greg_e |
But what signal gets sent to the speedo to make the indicator move? Is it just the raw pulses from the speed sensor or is it some kind of signal from the computer. I saw a brief mention of testing the gauges with the signal while I was flipping through the service manual for something else, so I'm guessing it is something like a PWM signal that varies in frequency. I was just hoping that someone would know what it was so that I could plan on making some sort of micro controller to handle the conversions. | ||
| Blake |
Hook it up, test it. | ||
| Greg_e |
I was just hoping someone had walked this road before me. Might need to get a better oscope for this. | ||
| Blake |
Bill (Reepicheep) is somewhat familiar with the speedo output. He designed a filter to prevent voltage spikes from causing trouble; Buell soon followed suit. I'm pretty sure that the signal is just a voltage pulse, around 5V if I recall correctly. Unfortunately, the parts book and service manual don't go into detail on the sensor. Hmmm, maybe a bit more complex than a simple pulse direct from the sensor, and now maybe 12V instead of the 5V I misremembered? See the following: http://www.badweatherbikers.com/cgibin/discus/show .cgi?tpc=3842&post=170040#POST170040 | ||
| Reepicheep |
I was interested in hearing what other people figured out!  I know the hall effect sensor on the speedo sensor just puts out a pulse train that I think is based on 5th gear (which is always turning at a constant proportional speed relative to the rear wheel on the output shaft. So I suspect each tooth gives a pulse. What I don't know is if the ECM massages those pulses and outputs something different to the speedo. I doubt it, I suspect the speedo just eats those pulses and translates them to a speed. One of us should hook up a scope and see... | ||
| Blake |
Just received the following from Herr Gunter: speedo signal is a 0-5 volts ttl-compliant hall-sensor square pulse. Thanks for looking in on us Gunter! | ||
| Greg_e |
Ok, so it looks like I am still at the point of having to scope the signal to the speedo and see what is happening, then sampling the pulses from the HALL with a microcontroller and converting that to the correct output for the speedo. The advantage is that I can change gear ratios and tire sizes as I want and still get accurate calculations since I'll be doing the programming. I wonder if it might be useful to just switch both gauges for something that would be easier to deal with. I guess I'll burn that bridge when I get closer to buying the MicroSquirt system and sensors. Might be time to put in a completely digital dash as it might actually save a few dollars and countless hours. I'll have to get a really good stand so that I can idle the bike in gear to look at the pulses. Hate to do it, but riding around with an oscope attached to the bike might be difficult. Wish I owned a dyno. | ||
| Blake |
Do you really need a tach? Speedo by GPS is a handy solution. | ||
| Greg_e |
The tach is the easy part if I go to an aftermarket type that just takes pulses. Might need to do the same for the speedo. | ||
| Reepicheep |
It would be straightforward to whip up a speedo converter from a PIC microcontroller. $5 to $10 worth of parts, all said and done. | ||
| Greg_e |
I was thinking AVR, but yeah we are thinking the same things. |
