I'm posting in Electrical rather than Sportster as I think this may be more of a generic ECM/Speedo problem. From what I've read in various model forums it looks like recent speedo systems are all pretty much the same.
Here's the problem.
Have an '07 XL 1200L. It's a working bike with nearly 20K miles on it. Runs great with no serious problems in three years - except for this one nuisance that is making me crazy!
Last summer I had a first instance of the speedo just dropping to zero. You know the gig - no turn signal auto-off, rough/fast idle, check-engine light and stored low VSS output code. I read up on this and it seemed right on schedule. With that many miles, the VSS had a moderate amount of gunk on it, so cleaned it off and no worries. Hah!
A week later I'm out riding with friends and cracked the throttle pretty good off a stop light and right up around 5K revs the speedo just drops again. Okay. Pull over, turn it off, count to ten, start it back up and everything is fine again. Until I hit the throttle wide open and bang, it will drop to zero every time. BTW, there will be NO stored diag codes until I ride it long enough for the ECM to figure out something is wrong and turns on the "check engine" light, e.g. everything reads like the bike is going 100 MPH but the VSS system says it's standing still.
So, I read up some more on this and find a lot of folks with newer machines are reporting voltage regulator problems related to speedo dumps as the voltage output is too high at full revs. Okay, this makes sense so in goes a new voltage regulator (this is after having it to my local dealer - good guys - and they can't find a thing wrong after putting their break-out on it and riding it for a while). Now the problem changes but is just as repeatable. I can run the bike all day at 6K and the speedo will never dump. BUT, come to stop light and give it a little too much juice from a dead stop and bang, now the speedo dumps at maybe 20 MPH. Having changed the voltage regulator and cleaned the VSS, I decided to go for another $50 and replaced the VSS. No change at all.
I can make it dump this way all day long and never see a diagnostics code get recorded so long as I reset it quickly. For instance, if I make the mistake of starting a little too quickly (it seems to never dump if I baby it off the light but can crack the whip once I'm in second gear all I want) and see the speedo dump, I just give it a bit more speed, pull in the clutch, flick off the run switch, count to three, flick the run switch back on and the speedo reads correctly again and I restart the engine all in a distance of 100 yards or so.
Weather's been rainy here the past week or two, so I took some time to pull off the seat and tank and traced the wires for this circuit. It looks pretty straightforward. Three wires between the VSS and ECM - looks to be power/ground/output. I'm assuming that the VSS output signal is interpreted by the ECM and sends the appropriate signal to the speedo.
End of story or am I missing something? I rang out the lines disconnected for possible ground/line-to-line shorts and they all checked okay as did end-to-end continuity. My dealer wrenches say replace the speedo next but I'm thinking it's the ECM or something else I'm missing. Has anyone else had this experience? I've even taken it out on some really bad roads to bounce the (EDITED) out of the machine (painful on a low) to see if it would cause the speedo to drop out. That is, the dealer guys think that perhaps the first gear jolt of too much throttle indicates a mechanical problem internal to the speedo which resets when the ignition is cut off and back on. But the speedo held steady after many rides down the bumpy road which is making me think it an ECM problem. I'm just hoping there aren't a dozen other inputs the ECM uses in addition to the VSS input to generate a speedo signal.
It would be great if someone else has had a similar experience that could yea or nea on this or offer some other explanation.
Thanks in advance and sorry for the length of the story but its an odd one.
Language is not permitted on this forum.
Please read and understand the info in this link...
Here's the problem.
Have an '07 XL 1200L. It's a working bike with nearly 20K miles on it. Runs great with no serious problems in three years - except for this one nuisance that is making me crazy!
Last summer I had a first instance of the speedo just dropping to zero. You know the gig - no turn signal auto-off, rough/fast idle, check-engine light and stored low VSS output code. I read up on this and it seemed right on schedule. With that many miles, the VSS had a moderate amount of gunk on it, so cleaned it off and no worries. Hah!
A week later I'm out riding with friends and cracked the throttle pretty good off a stop light and right up around 5K revs the speedo just drops again. Okay. Pull over, turn it off, count to ten, start it back up and everything is fine again. Until I hit the throttle wide open and bang, it will drop to zero every time. BTW, there will be NO stored diag codes until I ride it long enough for the ECM to figure out something is wrong and turns on the "check engine" light, e.g. everything reads like the bike is going 100 MPH but the VSS system says it's standing still.
So, I read up some more on this and find a lot of folks with newer machines are reporting voltage regulator problems related to speedo dumps as the voltage output is too high at full revs. Okay, this makes sense so in goes a new voltage regulator (this is after having it to my local dealer - good guys - and they can't find a thing wrong after putting their break-out on it and riding it for a while). Now the problem changes but is just as repeatable. I can run the bike all day at 6K and the speedo will never dump. BUT, come to stop light and give it a little too much juice from a dead stop and bang, now the speedo dumps at maybe 20 MPH. Having changed the voltage regulator and cleaned the VSS, I decided to go for another $50 and replaced the VSS. No change at all.
I can make it dump this way all day long and never see a diagnostics code get recorded so long as I reset it quickly. For instance, if I make the mistake of starting a little too quickly (it seems to never dump if I baby it off the light but can crack the whip once I'm in second gear all I want) and see the speedo dump, I just give it a bit more speed, pull in the clutch, flick off the run switch, count to three, flick the run switch back on and the speedo reads correctly again and I restart the engine all in a distance of 100 yards or so.
Weather's been rainy here the past week or two, so I took some time to pull off the seat and tank and traced the wires for this circuit. It looks pretty straightforward. Three wires between the VSS and ECM - looks to be power/ground/output. I'm assuming that the VSS output signal is interpreted by the ECM and sends the appropriate signal to the speedo.
End of story or am I missing something? I rang out the lines disconnected for possible ground/line-to-line shorts and they all checked okay as did end-to-end continuity. My dealer wrenches say replace the speedo next but I'm thinking it's the ECM or something else I'm missing. Has anyone else had this experience? I've even taken it out on some really bad roads to bounce the (EDITED) out of the machine (painful on a low) to see if it would cause the speedo to drop out. That is, the dealer guys think that perhaps the first gear jolt of too much throttle indicates a mechanical problem internal to the speedo which resets when the ignition is cut off and back on. But the speedo held steady after many rides down the bumpy road which is making me think it an ECM problem. I'm just hoping there aren't a dozen other inputs the ECM uses in addition to the VSS input to generate a speedo signal.
It would be great if someone else has had a similar experience that could yea or nea on this or offer some other explanation.
Thanks in advance and sorry for the length of the story but its an odd one.
Language is not permitted on this forum.
Please read and understand the info in this link...
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