Harley electronic speedometer help

[nosaj]

Also of interest.
nosaj

[nosaj]

Sticky needle?
nosaj

[nosaj]

Ok how about a model and any relevant info. If appears there could be a diagnostic access somehow. That may give you what your looking for
nosaj

[Mick Bailey]

I wonder if one of the free oscilloscope apps for a phone would work using a coupling capacitor and resistor to ground. Some experimentation may be required to visualise the output and it isn't something I've tried. I'm thinking maybe a 10nF cap in series followed by a 100k resistor to ground.

The ideal method of doing this is using data recording or data acquisition. This got me thinking that a $3 Arduino could be programmed to light up a high brightness LED if the speedo signal showed any abnormality - a firmware missing pulse detector.

[g1]

A different approach would be running a square wave into the speedo.

[Randall]

I am asking about the source pulses to my speedo, I am not interested in the tach right now. I want to see the pulses. I want to see if they change or distort or go away when speedo dies. A rigged up tach won't tell me much of this.

I am well beyond reading posts from cycle sites. I have done the searches, read the dead end posts, and this question is over their heads. It ends up being either replace sensor or replace speedo. This does not always fix it.

Anyone who read my original post would see that the sensor is newly replaced, and that the +12v going to it is sound. It is NOT the problem.

My speedo does not have any diagnostics, none on this 30 year old bike whatsoever.

If you read my original post, you will find I also plan to bench test it with an Arduino based square wave generator (when it arrives). But this tells me only a part of the picture. As in, what if I hook it all up on the bench. and it works for a while? I already know this part, it will work until it doesn't. And it does not simulate road use. Nor does it tell me if the signal is getting lost or not while on the bike and on the road after some miles, a point I don't seem to be articulating well enough for this group of very smart fellows to focus on. Frustrating to say the least.

Thank you for your consideration guys, but I will take it from here.

And if one more person says. "I would check grounds and all other connections", I swear I will catch on fire.

[g1]

You've received some good suggestions, which do not warrant you being so dismissive.
What if you tried something with the tach and it did cut out?
What if it cuts out with a square wave?
You are severely limiting valid and reasonable suggestions. All you care about is seeing the waveform? No, you can't do it at your price point.
Take it from there.

[Randall]

If anyone sees me as being dismissive or seriously limiting in my responses, then I respect that. But I disagree.

I did not come to this empty handed, and I did have a very specific question didn't I? Being referred to an Australian Toyota site, or any of the other entry level forum posts that do not actually address my specific question is frustrating for me. I have been there and already done all of those things before I came to you guys. I use a Harley forum that is as good as this one that I have bounced this around in for a couple of weeks. They are great at cams and valves and carbs, but you guys are great at electronics. I didn't expect to get an electronic specific answer from them, and I am not looking for motorcycle advice here.

I see now that I should have never used the word speedometer. It just threw the hounds off the trail. I should have just asked the specific electronic question and not said why, which would have limited responses more precisely. I'll take take responsibility for that as a teaching moment.

I can think of three suggestions from you gents that are relevant to the question. Hand held portable meter for a single use, which is not a realistic cost option for me at this time. Rigged tach, which maybe might work, maybe not, and wouldn't really give me what I seek, a waveform. Not to mention not wanting to try to run both a tach and a speedo from the same 0-5v signal with the issues that it might introduce, or the complete lack of scale adjustment. I don't really see that as a win. And a possible o-scope phone app, and since I cannot see my phone screen outside on a good day, also doesn't make me want to jump right on. I wouldn't know how to do it anyway, not being a phone guy. And yes, sure, it MIGHT work, so why not try it? I won't bore anyone with why I don't care for that idea much in this case.

Driving the speedo with my own square wave was always part of the plan, albeit a flawed plan. Also, It won't tell me a whole lot, but probably worth the effort anyway. It's quite hard to duplicate riding conditions on a bench.

So if the answer is it is not going to happen at my price point, then so be it, there is my answer. Why not just say that earlier than later?

I would still be open to any suggestions that are relevant and don't pull the discussion backwards over already covered ground. I am sorry if I did not articulate this well enough.

Hope you Florida guys make it thru this heavy wetting coming thru.

edit: I just found some really inexpensive Chinese handheld o scopes. Did not understand them to be this affordable, I was thinking around $100 or so, not ~ $25 . Although about half of them are on known scam sites, so there's that. But I will look into this option further. Could be exactly what I seek.

[nosaj]

Ah we be dry here wont see a bit of it.
nosaj

[g1]

Ok. Well, you didn't give us a price point off the top, so it didn't come up til later. 50 bucks does not seem like a lot for something that can be useful for other things, but that's just me.
The speedo is a known issue. I was looking for some way to simply verify it as bad, which may not require seeing the waveform. If you could make it fail off the bike, say after 10 minutes, I think that would be a valid indicator of a bad speedo.

I don't know what is involved with the speedo removal. I'm sure you have considered trying yours on someone else's bike, or their speedo on your bike.

[Mick Bailey]

The cost of replacing motorcycle clock is insane. My friends 5 year old Moto Guzzi had a failed tachometer - a cheap plastic pod weighing almost nothing. £660 ($840) replacement cost. He got it repaired for a third of the price but still a hefty chunk of money.

I did think of offering to repair it, but it looked to be a problem getting into it as the chrome bezel had to be removed and it's crimped onto an ABS shell so there was the risk of marking it. The specialist company he sent it to looked like they'd levered it off with a screwdriver.

[John_H]

I've used GPS speedos on my dual sport motorcycle and my sandrail with good results

https://www.amazon.com/Speedometer-D...25&sr=8-3&th=1

[Mick Bailey]

I didn't know they could be had so cheaply. Seems to be a good addition to my wife's imported bike that has a Kph speedo overlaid with stickers on the glass face. You can be doing 45, 55 or anything in between just by moving your head.

[Randall]

Not easy at all to remove/replace speedo, or especially to get it apart. As mentioned it must be carefully pried apart. Using a new sharp small nail removing claw seems to be a favorite method. And before I attempt that, I want to see that darn waveform, but we've been thru all that. Bench testing would be secondary, (as I have already made plans to do) because I need to rule out or not the wiring harness.Maybe it works fine on the bench, but not when connected to the harness. And anyway, who has time to watch a speedo on the bench for a glitch here and there? So, a secondary approach with less than water tight results there.

No, I have not tried swapping with another bike. I have no real way to do this, and they are not all exactly plug and play as far as connections go.

I will try my luck at a portable scope when I have the funds. Medical bills have me in a fetal position at the moment. At this point in my declining health and career, I don't ever envision needing it past this one use, and will probably get rid of it once this is resolved.