Erratic speedometer

[kenney158]

I have checked other posts, but not finding my exact situation. Travelling across very hot midwest (temps high 90s). Speedometer periodically jumps all over the place- actual speed between 60-75 but needle waves as high as 120 then drops but continues to waver. This lasts a few minutes then seems to return to normal.

Driving is not effected- so far. RPMs around 3,000. No change in power or speed.

I've seen posts suggesting the VSS may be bad- 2 questions- 1) how likely is it that the VSS is the culprit, and 2) what does the VSS effect besides the speedometer- does it communicate with other parts, e.g., engine or trans? Will there be eventual driving problems? (Okay, 3 questions.)

One post suggested possible low trans fluid level. Is this a possible cause?

Info is appreciated- especially since I'm on a 3 week road trip-

[TDCTDI]

It sound like a VSS, a bad one is quite annoying when you are using cruise control.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kenney158]

I can live with the annoyance- I'm avoiding cruise control since I don't know whether it is part of the problem. More concerned there will be some other related problem.

[TDCTDI]

Low fluid isn't going to cause wild swings of the speedometer.

Cruise control gets it's signal from the VSS via the instrument cluster so that will be affected.

Depending on year, the ABS & TCM can get weirded out by a failing VSS.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kenney158]

It's an 03 weekend. Not too concerned about ABS. TCM is what? Control module I know but can it be driven? Odometer of course is reacting to speedometer. Looks like I'm going3 miles when I go one?

[CdnVWJunkie]

TCM= trans control module.

I second the VSS. Could be some "gunk" collected on the magnet on the tip.

[kenney158]

I'm. So tcm is important. If running ok can it be driven? Where is the bad? Can I reach it easily enough to clean it?

[kenney158]

Hate autocorrect. Where is the vss?

[TDCTDI]

The VSS is on the top side of the extension coming off the passenger side of the transmission.

You shouldn't be doing any harm to anything by driving it, you might get some erratic shifting due to final drive correlation.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kenney158]

At a dealer now. Tech says the weird signal could be due to a plastic cog inside transmission- which of course requires a tear down. No code coming from bad but could be going bad- just not enough yet to throw a code.

[TDCTDI]

There's no "tear down" necessary! Replace the sensor, it's on top, no need to pull shit apart first. The sensor drive gear is easily removed AFTER you take the VSS off. If they try to charge you any more than 1 hr (typical dealer minimum charge), they're bilking you. Fu*&%ng weasel bastards.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kenney158]

That's the plan. Replace sensor first and see if that corrects it. Would only do tear down if it doesn't.

[TDCTDI]

If the plastic drive gear is bad, the sensor doesn't turn so therefore, no signal/no speed registered.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kenney158]

Good to know. Tech suggests drive gear may be in process of going bad so slipping at times. But will see if sensor can do the job first. Of course, getting the parts is tough in Missouri. Laid up for now. Not will to continue the trip with chance of getting stuck on the high plains of Kansas with no shop in sight. Thanks for your help.

[kenney158]

Just saw your post about the gear being accessible once the sensor is removed. Very helpful. I will use that when I talk to them about the job-

[tkbartscherer]

I had the same exact issue and I fixed it myself.

It was a bad engine ground by the ignition coil on my 1999 Eurovan Camper. Fixed it immediately and for free. Check all grounds before anything else. This should help. Good luck!

[kenney158]

Thanks TK. Haven't communicated with dealer yet so don't have an update. I will definitely ask them to check grounds. I've been wracking my brain for causes- power washed (at the car wash) undercarriage before my current trip. Seems unlikely but wondering whether high pressure hoses/degreaser either spread gunk to sensor or may have effected a ground. Seems like a reach given that the pan was in place and got most of the spray hit there, but don't know what may have splashed around under there.

Will definitely point out the chance of a ground problem.

[kenney158]

Left my EV at the dealer for more than a week while finishing my trip. Back at dealer now and being told transmission is needed. Blaming this on a leak and low fluid level. Van shifted fine when I left it here- except for some kick down from 4th to 3rd with the erratic speedo/VSS problem which brought me to them to start with. Feeling very mistrustful of dealer now. Seeing some fluid on pavement under van now- didn't have that when I left home 1200 miles ago.

As I understand it, erratic speedometer would have nothing to do with low fluid or trans problems. They have yet to repalce the VSS, so have no info on whether that corrects speedo problem. Tech reportedly drove it "20 minutes at 70-75 mph with no problem with speedo"- claimed it shifted rough, but again, I had no such experience.

Anyone with knowledge of Lee's Summit VW in Missouri?

How about Das Autohaus in Lawrence, Ks? Thinking of having it towed there for a second opinion. Will drive it tomorrow to look for rough shifting.

Any recommendations on reputable EV mechanics within 200 miles of Kansas City are welcome.

[kenney158]

Also wondering about Volkswerks in Shawnee, Ks.

[TDCTDI]

The VSS can be very sporadic & May only act up after an hour of driving, every third day, why didn’t they replace it?
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.