Rubbermount_EVO Bad Speedometer or Bad VSS?

[cookiemech]

I've now run my new-to-me 2005 Roadster more than 1000 miles since picking it up in January (and putting in a lot of work bringing it back to stock configuration). Bike was sadly neglected and sloppily modified, but it now looks good and runs very well.

I don't think anyone ever changed the primary/gearbox oil or engine oil in its 11K miles, so I changed both of them cold before I ever ran it. Of course there was a lot of slime and "whiskers" on the primary magnetic drain plug. Yesterday I changed both oils again as I had just run it and everything was plenty hot. Engine oil was again filthy, but the primary/gearbox oil was clean. Some whiskers on the drain plug, but no chunks.

The issue is that the speedometer sometimes drops out. By that I mean that the needle will drop from the current speed to zero and the odometer will stop incrementing. Backlight stays on and the odometer reading remains wherever it stopped counting.

Usually (but not always) this happens as I slow to a stop. The most common scenario is that at maybe 10 or 15 mph, the needle drops abruptly to zero and stays there, even after I pull out and accelerate. Generally as I accelerate to maybe 35 mph or so, the needle jumps back up to the proper speed and the speedometer behaves until the next stop. But once in a while it drops out while just cruising at moderate speed.

There seems to be no correlation whatever to bumps in the road (of which there are many in Pennsylvania).

At one point I removed the vehicle speed sensor and wiped it off. There was nothing remarkable about the way it looked. I do have a new VSS on the shelf, but before installing it I wanted to see if anyone else has had a similar speedometer issue.

Should I take the speedometer apart to look at the connections inside the unit?

[Tomcatt]

Originally Posted by cookiemech

At one point I removed the vehicle speed sensor and wiped it off. There was nothing remarkable about the way it looked. I do have a new VSS on the shelf, but before installing it I wanted to see if anyone else has had a similar speedometer issue.

Simplest place to start is to try your new VSS and see if that fixes the problem.
Check your new batteries' connections to make sure they're tight...

[rejeanprimeau]

Look like loose or corroded wire, the VSS is voltage sensitive, bad connection behave like you stated. Also, always check battery connection before anything else.

[IXL2Relax]

Originally Posted by cookiemech

I've now run my new-to-me 2005 Roadster more than 1000 miles since picking it up in January (and putting in a lot of work bringing it back to stock configuration).
<SNIP>
Should I take the speedometer apart to look at the connections inside the unit?

NO! That's not a likely solution (unless a DTC indicates speedo failure) - The VSS signal (analog) is fed to the ICM, then the speed information is sent from the ICM (using the Serial Data Link) to the Speedometer. This is digital information, not an analog signal.

==================================

Did you check the Diag Codes? What was reported?
http://sportsterpedia.com/doku.php/t...ing_dtc_codes1


When you're having issues with the electrical system, use this Sportsterpedia section about
checking the battery cables, voltages and grounds - DO THIS AS MAINTENACE, TOO:
http://sportsterpedia.com/doku.php/t...place_to_start

Be sure to check the Powertrain ground as the VSS sensor is grounded there. This is not the likely source of your problem because other things would be going out as well. There have been corrosion issues with the PT ground stud in the case. Moving it to the rear of the Primary Cover is suggested.


Here's information about the VSS:
http://sportsterpedia.com/doku.php/t...e_speed_sensor

It shares the 5v Sensor Power with the CKP Sensor. This voltage is generated from the ICM.
Clean the ICM connections.

You probably want to replace the VSS (since you have one) to see if that resolves the issue (or for general maintenance reasons).

It would be a good idea to open, clean, dielectric grease the VSS & CKP Sensor connectors.

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For Sportster Tech Info:
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[cookiemech]

Originally Posted by IXL2Relax

Did you check the Diag Codes? What was reported?

Yes. No codes.

When you're having issues with the electrical system, use this Sportsterpedia section about
checking the battery cables, voltages and grounds - DO THIS AS MAINTENACE, TOO:
http://sportsterpedia.com/doku.php/t...place_to_start

Did all of that while going over the bike in January. Battery and both positive and ground cables are new OEM H-D. Routed cables correctly, torqued battery bolts to spec, zip-tied ground connection at battery.

Be sure to check the Powertrain ground as the VSS sensor is grounded there. This is not the likely source of your problem because other things would be going out as well. There have been corrosion issues with the PT ground stud in the case. Moving it to the rear of the Primary Cover is suggested.

Yep. Took the ground stud out, cleaned up. Cleaned up terminal ends. I use DeOxit liberally.

Here's information about the VSS:
http://sportsterpedia.com/doku.php/t...e_speed_sensor

It shares the 5v Sensor Power with the CKP Sensor. This voltage is generated from the ICM.
Clean the ICM connections.

Yep. They were clean, but got the DeOxit treatment.

You probably want to replace the VSS (since you have one) to see if that resolves the issue (or for general maintenance reasons).

Replaced it half a hour ago. Hopefully dry tomorrow for my usual 70-mile loop to test it.

It would be a good idea to open, clean, dielectric grease the VSS & CKP Sensor connectors.

I've opened both previously and used DeOxit. VSS connector still looked perfect today.

Thank you for such an extensive response. Glad to read that a defective speedo should throw a code!

[IXL2Relax]

I don't have one of the new-fangled models, but:

Originally Posted by cookiemech

Glad to read that a defective speedo should throw a code!

Did you do the WOW test? Passed?
http://sportsterpedia.com/doku.php/t...k:ref:genmsr08

Internally, the speedo has no replacement parts. You could disconnect the speedo connector, clean & replace just as a preventative.

Even if the system normally shows no codes and the WOW test works, if the internal operation of the speedo is malfunctioning, I don't think any codes would be set. Being intermittent adds to the difficulty of troubleshooting the source of the problem.

When doing the code checks --- the SP value will display the speedometer model firmware information - Did that come up?

I think you should get a code if the Serial Data Link information from the Speedo fails.

It might be worth putting a meter on the 5v Sensor Power line (at either the VSS or CKP or both) to see what voltage level it is running.

Good Luck - I hope the replacement VSS clears things up...

IXL _______ >>>> My Motorcycle Chronicles Are Here <<<<
For Sportster Tech Info:
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[cookiemech]

[QUOTE=IXL2Relax;5988530]I don't have one of the new-fangled models, but:

Did you do the WOW test? Passed?
http://sportsterpedia.com/doku.php/t...k:ref:genmsr08

Yes. Passed.

Internally, the speedo has no replacement parts. You could disconnect the speedo connector, clean & replace just as a preventative.

I'll do that next, if tomorrow's ride does not show proper speedo functioning.

Even if the system normally shows no codes and the WOW test works, if the internal operation of the speedo is malfunctioning, I don't think any codes would be set. Being intermittent adds to the difficulty of troubleshooting the source of the problem.

When doing the code checks --- the SP value will display the speedometer model firmware information - Did that come up?

You mean when it shows part number? It did show that.

I think you should get a code if the Serial Data Link information from the Speedo fails.

It might be worth putting a meter on the 5v Sensor Power line (at either the VSS or CKP or both) to see what voltage level it is running.

Good Luck - I hope the replacement VSS clears things up...

Thanks again!

[cookiemech]

I am cautiously optimistic. Just returned from a chilly 80-mile ride and there were no speedo issues at all. First time ever that it didn't drop out.

I appreciate the advice!

[IXL2Relax]

Originally Posted by cookiemech

I am cautiously optimistic. Just returned from a chilly 80-mile ride and there were no speedo issues at all. First time ever that it didn't drop out. I appreciate the advice!

Thanks for the update - It's good to hear that.

I hope that result continues.


IXL _______ >>>> My Motorcycle Chronicles Are Here <<<<
For Sportster Tech Info:
Ride On The Sportsterpedia - A Toll-Free XLForum Information Highway!