Speedometer dance/bounce

[elduderino200]

Lately my speedometer needle has been dancing/bouncing, even when at a constant speed. Does anybody have any ideas?

It's pretty old and I could use a new LCD screen anyway, but is this just an electrical connection issue that could possibly just need a solder re-flow? Or is there a mechanical issue?

This video is me driving at near constant 30-32mph (slowing down at the end to turn)

[cactus_cars]

Lately my speedometer needle has been dancing/bouncing, even when at a constant speed. Does anybody have any ideas?

It's pretty old and I could use a new LCD screen anyway, but is this just an electrical connection issue that could possibly just need a solder re-flow? Or is there a mechanical issue?

This video is me driving at near constant 30-32mph (slowing down at the end to turn)

I actually bought this speed sender https://www.fcpeuro.com/products/aud...1d#description for my B5 1.8T 01A trans car, but never installed it. I had this problem mainly when coming to a stop in the cold (~34 deg f), and then starting quickly. Was maybe be due to the very viscous Amsoil extreme manual tranny fluid I put in it which made the 1-2 shift, much, much better, and the rest seems to be my crappy push down shift linkage.

It randomly decided to stop one day and I never saw it again. That part is a bargain though @ $12. Not sure if you have a manual or auto though. The auto will have a different impulse sender.

Wish I could be of more help though. An electrical connector on the sender was also one of my suspicions.

Let me know if you figure it out.

[mobildetroit]

Suspect it's the vehicle speed sensor or a loose ground...although if it's a loose ground I would expect to see more mayhem in the dash console because I believe the cluster all grounds at the same point...so if that ground is loose everything would likely freak on the dash cluster. If it's just the speedo, then likely the circuit that drives the input signal for it....thus speed sensor. Could try just taking it out and cleaning the speed sensor, could have metal filing deposits due to normal wear....I believe it may be magnetic, which is why...clean it off, put it back in, may smooth right out to normal again.

[elduderino200]

Thank you both for the help!

Sorry two things I forgot to mention:
the first thing I did was replace the speed sensor with brand new from ECS.
second, it appeared to happen (but could just be a coincidence) when I did a light pressure wash on engine bay to get leaves out. Nothing major, just a quick shot or two of a spray near the battery for some extra debris. Though it started right up after and saw no other issues.

I'll go back and check grounds and any other obvious concerns (though I believe I checked sufficiently)

[elduderino200]

Good news! I finally got around to replacing the speed sender as cactus_cars mentioned, and it seemed to have solve the issue.

The other good news is that if you have a 1.8t, you can reach down from the top and this seems like a super simple job (as seen here: https://www.youtube.com/watch?v=mwvsviNEsNI)

If you have a 2.8 like me however, start praying... You can't reach down from the top so you'll need to pull off the drivers side wheel. From there you can see it right where it connects to axle, but releasing it is another story. There should be a small guard just above it that protects the inner CV joint, and that will need to be removed. Unfortunately there's 3 bolts holding it on, two are easy to get but one is at the top and NOT easy. I ended up stripping that because I couldn't see what I was doing because there's NO way to get two hands up in there as well as a way to see. If you are lucky enough to get it off, you can probably push the plastic tab on the old sensor down and spin it 90 degrees to remove it, but if you CAN'T get that guard off (I couldn't), you'll need try to use whatever you can to press down the little tab through the hole that locks it into place, then rotate it. Since you're replacing it, you can break the whole tab off entirely then just spin what's left of the sensor with your hands or pliers, but you still need to get the new one in, tab and all. It can be done! But it will need to be wiggled in correct under the guard and with the tab pressed a bit so it fits, all of course, with very little room for one arm, let alone two.


(if I don't come back here to write another reply, the sensor replacement was the fix!)

[Cybersombosis]

A point of note, check the connector for corrosion. I replaced one on a customers car and still had speedo issues afterwards. Took a look at the connector and sure enough there was oxidation. Took a file and some contact cleaner and finally put some dielectric grease on and stuck it on and pulled it off multiple times to get it to mate properly.

[elduderino200]

Sad to say I'm back.


It seemed to work great for the first 10-15 miles while testing, but when I drove to work the first time it skipped a few times then finally settled at 0 and didn't come back to life until I parked for the day and drove home. Even then it was jumping around like before.

Another interesting note: my gas gauge is doing something similar. It's not quite jumping to the extreme, but definitely waving around.


I'll pull the connection again and check (that was easy - just remove the wheel) for corrosion as Cybersombosis suggests, but I'm not terribly confident that will solve it.

[cactus_cars]

Huh. I'm fairly certain that the gas gauges do that, mine does that especially when parked on an incline. Usually solved by cleaning the fuel level sender (Audi made the part NLA ~2 months ago) and then re-installing. There are a few decent youtube videos for doing it. I haven't got around to that as my engine blew up on tuesday. Rod Knock I bet.

I would chase the connector and the wiring up and inspect for damage (speed sender).

[Mattr567]

The gas gauge will move a bit depending on inclines, but nothing crazy jumping around or extreme differences.

Worst case could be the cluster, if it's been apart by someone it's easy to mess up the stepper motors. But more likely something else. Bad sensor out of the box maybe? Did you get a good brand from ecs? Lots of garbage out there these days.

Mine is all original at 175k, sensor has always worked perfectly.

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[elduderino200]

My cluster hasn't been opened to my knowledge and unfortunately I just hit 180k and hadn't had this problem until now.

The sensor was from FCPEuro so I think it's good? Exact same symptoms of the original which I feel would make it unlikely to be a bad sensor.

I was able to get the shield above the axle finally off (side note: if you have a 2.8 and can get the two side bolts out but not the last top one, the shield is probably old and brittle enough that you can break off the entire thing by bending it up. Then you can actually see the final bolt and use vice grips if it's stripped. Just put the shield back with the two side bolts). I can now quite easily remove the sensor and pull it out if necessary.

I traced the wires back up and it looks fine. I also pulled the speed sensor back out and it seems fine (as it's brand new as well).

Is there a reason there seem to be two holes for the speed sensor? I finally got a look at the area and there's two holes that are exactly the same that poke into the flywheel. I didn't grab a picture but now I'm second guessing everything.

I've found the speedometer generally seems to act worse when the car warms up and at higher speeds. First 10 minutes of driving it's golden but as it warms up it seems to do worse at lower speeds and usually seems to do worse on the highway.

Is there a chance it could be the transmission fluid? Low? Or quality? I changed it for the first time but probably 4-5 years ago and I don't remember which brand but it I made sure it was something halfway decent.

[elduderino200]

Circling back here...

Is there any chance this could be a cluster issue? It's quite clear this works 100% of the time for the first 10 minutes the car is on, regardless of speed. Then very rarely after 10 minutes of driving. My suspicion is heat is messing with some broken solder connections in the cluster. I was already planning to get the LCD replaced so I was hoping if it was already getting sent in, I could have someone look at the speedo - or is that even a thing they can do? Everything seems to only show lcd replacement.


Secondly, if it's heat related, could it be the transmission fluid heating up? I can't really tell what else it could be.

[maxiz1]

Circling back here...

Is there any chance this could be a cluster issue? It's quite clear this works 100% of the time for the first 10 minutes the car is on, regardless of speed. Then very rarely after 10 minutes of driving. My suspicion is heat is messing with some broken solder connections in the cluster. I was already planning to get the LCD replaced so I was hoping if it was already getting sent in, I could have someone look at the speedo - or is that even a thing they can do? Everything seems to only show lcd replacement.


Secondly, if it's heat related, could it be the transmission fluid heating up? I can't really tell what else it could be.

Have you tried hooking up a scan tool and view the live data on the vehicle speed? On some cars, the data is also fed from the wheels abs sensor. If the data is ok, then I would say it is the cluster problem

[elduderino200]

Ah good plan I should try that. I didn't pay $200 for the vagcom to collect dust

[elduderino200]

Quick update:

Hooked up the sensor and it was also dropping to 0 mph when the needle dropped, so thank you to maxiz1! We've eliminated my suspicions it may be the cluster.

Now back to square 0-ish.

Next time I have a minute, I'll check the cables again. Both of the crankshaft position sensor and of the impulse sender. When I last checked, both seemed fine but I'll check again. After that I don't know what to try besides replacing either or both (again). Both have been replaced since this started: Crankshaft sensor was Bosch from ECS so hopefully that was fine, and the impulse sender was "VNE Automotive" from FCPEuro (here: https://www.fcpeuro.com/products/aud...sor-012409191d). It could be that, but after replacing I had the exact same symptoms so it's hard to say.
I can also replace the manual transmission fluid.
If it aint one of those three, I'm not sure.

[elduderino200]

Another update: I chose to throw money at the problem and replace the impulse sender again (this time with a different brand), as well as replace the transmission fluid.

Sadly neither worked. This time it took less than a block for my speedo to stop working entirely (usually it takes 10-15 minutes where it then starts bouncing around for another 10-15 minutes then finally fails for good by dropping to 0). I figured the sensor may have just been bad, or because of the odd delay for it to start happening when driving, it was the fluid that would heat up and cause issues. Clearly neither of my theories were right. The small silver lining is it shifts quite a bit more smoothly.

Unfortunately with so few things it can actually be (impulse sender, crank position sensor, wiring, fluid?) I'm at my wits end. I've tried to follow the wiring up, but since the connection to the sensor is on the sensor itself (there's no tail like the crank position sensor), it's nearly impossible. About 3 inches up from the sensor/connection, it groups with some other wires in some plastic sheathing and disappears behind the engine. Since it's a 2.8, there is 0 room to reach behind and and look or move something out of the way to get a better eye.

With this stumping me and a brake caliper rubbing in the rear that I also haven't been able to diagnose (despite more time spent on it than this stupid speedo issue), I think it's time to stop putting much effort into the old girl and find something to replace it. A sad day for sure, but they don't last forever :(

[Cybersombosis]

Please take a picture of the connector for the impulse sender and post it up. Make sure to show the connectors inside the plug.

[ElBeano1.8t]

Recently at the shop i work at we had a ford van e250 that had an issue with the speedo as well. It was dead until it got up to 50-60 and shot up but then would die again. It ended up being the ECU had been fried when someone welded an exhaust without disconnecting the battery. Everything else worked fine but the speedo worked sporadically, might be something to look at.


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[ProfileTrader]

Is this speedometer sensor in the same location for the 2.8 AFC Engine with Manual Transmission (as I presume it has one too)? I did not know this sensor existed since I have been having issues but I received advice (not from this forum) to check the crankshaft sensor (the one that gets pulled to do the timing belt). That was not the issue.

By the way my issues are that the speedo and the tack do not work at the same time - or they do. It was intermittent but now it is most all of the time. Thanks

[Cybersombosis]

I just had a situation where my speedo went. I tried a new speed sensor, trans tone ring, testing the wiring to the cluster, then another tone ring. The crank position sensor has nothing to do with the vehicle speed but I tried that as a Hail Mary. I even swapped out ECU’s. One of the final tests I did was to have the car on the lift and with the ignition on, car not started, spin the front driver’s wheel and look for a signal from the vehicle speed sensor on the cluster. Sure enough, the speedo moved. I thought to myself, problem solved after the second tone ring. Went for a spin and still no movement on the cluster. WTF? From what I gathered, the OEM wiring somewhere along the line had interference or a noisy signal while the car was running not allowing the pulses of the sensor to reach the cluster so I wired the speed sensor directly to the cluster bypassing the OEM wiring altogether and now it works again. My original testing of the wiring was for continuity which passed and threw me in the wrong direction.

[ProfileTrader]

@cybersombosis - Very interesting. I hooked up my laptop to the OBDII and even when the cluster did not show any reading the laptop indicated my RPM. I did not test the speedometer as my laptop batter was blown but when the tach showed on the cluster the speedometer when it did not they both did not so I was confident had I driven with the lap top the speed would have show there too. I did test the connecting plug that plug into the cluster. Specifically the pin receptacle for the speedo and it showed 4.7v with where 5 was the target. So I think that was good. I tried looking for bad solder points and re-soldering the cluster. Did not work.

So my question - how did you wire the speed sensor directly to the cluster? Also would you have a picture of the location of the speed sensor. Thank you.

[Cybersombosis]

In my situation I had a tach reading and no speedo reading, either on the cluster or VCDS. The vehicle speed sensor, VSS goes to the cluster first then the ECU. When you looked at the tach with VCDS where you in the instruments module or the ECU module. If you are getting a speed reading in VCDS but not on the cluster, then that points to the cluster being bad.

For the wiring, I took a separate 3 pin connector and wired one wire to ground and the other to the cluster by removing the speedo pin in the connector and replacing it with a pin from another connector, bypassing the car wiring altogether. If I were you, I’d put the front left wheel up and spin it to see if your speedo moves before rewiring anything. But to me, it sounds like your cluster is on the fritz. Luckily I had spare parts to replace with and didn’t have to spend any money except when I replaced the tone ring which was $60.

[ProfileTrader]

Sorry for the late response, frustrating having additional issues. The OBD reader I have in my laptop is not VCDS so I am unsure if it is reading the ECU or the VSS. I will have to contact the company to see how it is reading the tach. Thank you for the info. I lean toward a bad cluster but will update when I tackle these other issues... more codes.

[ProfileTrader]

@cybersombosis Wanted to give an update. I checked with the company that I bought the software from and they said it reads the ECU. I was able to check both the tach and the speedometer and when both do not work on the cluster the software reads both and shows both. So as you said it is probably a bad cluster. So I will look to replace it with a decent used one and check to see who can change the odometer to match my old one.

[Cybersombosis]

Odometer can be changed with a cheapo eBay VCDS cable and Vag ERPROM programmer. Once you get the new cluster and test that the tach and odo work, then you can fart around with your old cluster for testing purposes. Once you learn how to do that, you can then change your good cluster. Always good to test with a spare cluster before farting around with your good one.

[ProfileTrader]

@cybersombosis Thanks for that... good idea. I will search for the ERPROM programmer and cable.