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speedometer reads ridiculously high (after trans rebuild)

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speedometer reads ridiculously high (after trans rebuild)

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Old 12-15-2017, 06:39 AM
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Default speedometer reads ridiculously high (after trans rebuild)

Canadian 1997 A8 4.2 Quattro
.
The speedo reads about 1.5 to 1.7x the speed from my portable Garmin GPS, so this is not a tire size issue. Reads 80 mph when the Garmin shows 52. I had removed the Canadian kilometers/h thin flexible plastic face under the needle on the speedo and installed one with both km/h and mph (US) so I could legally get the car into the US. Cut the plastic faces with scissors to take off the Canadian and put another from a used US speedo back on without disturbing the needle. The faces have the same range so that's not it. Maybe I did disturb the needle? (I don't think so, because the needle on the used US speedo was very firmly attached to its shaft, so much so that I destroyed the speedo (spring hanging out) it when trying to remove it. That's why I then used the scissors technique to just change the face with the numbers, keeping the old speedo. And it saved me from having to correct the odometer if I would've installed the used one with wrong mileage.)

I wonder if I screwed something up when I rebuilt the trans. (Well, I know I have a fluid leak somewhere near the front; it drips from the bellhousing, but that's another story.)

I don't know if it was correct before I rebuilt the trans, as I got the car with a blown trans.

My thought is to see if I can look at the pulses from the G22 vehicle speed sensor in some manner to see if they make sense. I also have a VAGCOM, so I'll see if that shows anything.

Any suggestions for me?
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Old 01-24-2018, 02:12 PM
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On my drive to work this morning, I hooked up VCDS.


- Cruise control on and holding at 95 km/h (speed according to Garmin GPS)
- VCDS reads mainly 110 km/hr, but jumping back and forth in a stepwise manner mostly between 110 and 88 km/h, and a few other values.
- Speedometer needle reads about 140 km/h
- Odometer reads 41.5 km for my drive to work today; Google maps predicts 42.0 km.

The variable VCDS reading and the high speedo makes me think the G22 vehicle speed sensor is sticking and/or the contacts bouncing. I don't know where any G22 signal damping is done, and by how much. Anyone know?

But the odometer seems OK. So I'm puzzled.

Any suggestions or clues for me?
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Old 01-24-2018, 10:43 PM
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Originally Posted by hillpc View Post

On my drive to work this morning, I hooked up VCDS.


- Cruise control on and holding at 95 km/h (speed according to Garmin GPS)
- VCDS reads mainly 110 km/hr, but jumping back and forth in a stepwise manner mostly between 110 and 88 km/h, and a few other values.
- Speedometer needle reads about 140 km/h
- Odometer reads 41.5 km for my drive to work today; Google maps predicts 42.0 km.

The variable VCDS reading and the high speedo makes me think the G22 vehicle speed sensor is sticking and/or the contacts bouncing. I don't know where any G22 signal damping is done, and by how much. Anyone know?

But the odometer seems OK. So I'm puzzled.

Any suggestions or clues for me?
Did you pull the needles from the cluster and this happened after? like next drive?
I'm thinking this could be the issue, the other thing could be the magnet in the diff that send the speed sensor a signal.
I damaged mine on my b5 a4 when I changed the diff bearing. (at least I attribute it to that since it worked properly before I changed the bearing)

Also, the mph layover could be different than the km layover that was stock.
Why not send you tcu to stukler for an immobilzer delete and put in a US spec cluster, they're cheap.
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Old 01-24-2018, 10:46 PM
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The issue is your overlay, look at the pictures, the KM/h does not correlate between the two clusters.
Get a MPH cluster and be done with it.

1997 didn't even have immobilizer in the US, does yours? if not a cluster swap will be simple and cost effective.

https://www.ebay.com/itm/1998-AUDI-A...VUySgN&vxp=mtr

Last edited by audinutt; 01-24-2018 at 10:51 PM.
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Old 01-25-2018, 08:39 AM
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Default The overlay IS different!

Originally Posted by audinutt View Post
Did you pull the needles from the cluster and this happened after? like next drive?
I'm thinking this could be the issue, the other thing could be the magnet in the diff that send the speed sensor a signal.
I damaged mine on my b5 a4 when I changed the diff bearing. (at least I attribute it to that since it worked properly before I changed the bearing)

Also, the mph layover could be different than the km layover that was stock.
Why not send you tcu to stukler for an immobilzer delete and put in a US spec cluster, they're cheap.
I was very careful not to pull the needles off. But yes, the overlays are very different. Needle straight up is about 100 km/h on the original, and 140 - 150 km/h on the US one. Exactly how much I'm off.

You solved my understanding; thanks!

The only drawback to putting a used US cluster into the car is that the odometer mileage will be wrong. This introduces complications into selling the car in the future. It's also not very straightforward to make the odometer correct, with the laws against odometer tampering, and willingness of people to do it, not to mention the cost. I had actually bought a used US cluster and installed it into the car to get it across the border from Canada. But the odometer complications made me simply remove the US overlay from the used cluster and paste it onto the original Canadian cluster and reinstall that before I titled the car in New Jersey: https://www.audiworld.com/forums/a8-...an-a8-2885859/. I think I destroyed the US cluster by trying to pull the speedo needle off.

Now you have shown me what's wrong. Thank you!

BTW, yesterday I ordered a new G22 sensor (under $9!) because of the VDCS showing the speed jumping around while I'm driving at a steady speed. It's very simple to change.

Not sure if I want to mess with the odometer reading and its complications upon swapping out with a US cluster, even though they are fairly cheap. I'm thinking of putting the old Canadian overlay back on, maybe after I draw some mph marks on it. Hokey, yes, but easy.

Thanks again for your help.

Last edited by hillpc; 01-25-2018 at 08:42 AM.
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