Adjust Speedometer: Calibration & Troubleshooting

I would like to adjust the speedometer reading to better reflect my actual speed. Currently, the speedometer shows a speed that is up to 15 km/h higher than my actual speed.

Is this possible with my model, and if so, in which stage?

In the speedometer

Does this need to be done in the software, or can it be coded?
Can't we program a different tire size into the ABS? After all, the signal originates from there.

You can try to code it, but it will hardly lead to the desired success. And the coding will not be done in the ABS, but in the speedometer. The speed signal comes from the wheel speed sensor, not from the ABS. This works on newer models, where you can tell the software: 'Get the signal directly via CAN from the ABS.' This doesn't work on older models. Therefore, the rest must be done in the software itself.

Where can I try coding? Do you have any tips?

You need to check if your speedometer supports it. See the values in the label file. Otherwise, the only option is to adjust it in the software .

bastion wrote:

I would like to adjust the speedometer reading to better reflect my actual speed. Currently, the speedometer shows up to 15 km/h more than my actual speed. Is that possible with my model, and if so, in which stage?

Hi,

I always adjust my speedometers by turning the speedometer needle to the left on its shaft. This allows you to completely compensate for a constant initial offset.

If your speedometer jumps to, for example, 5 km/h even when you're barely moving (e.g., letting the car roll slowly downhill), you can adjust the needle by rotating it 5 km/h to the left.

When dealing with a (remaining) proportional advance, you must choose where to place the "zero point": values below it will decrease, while values above it will increase.

I usually calibrate my speedometer needles to read zero at 50 km/h. Any remaining deviation has been minimal so far, with a maximum of about 5 km/h in the top speed range.
And whether the actual speed is 30 km/h, and the display shows 29 or 28... who would even notice?

"You're right, my expectation was also around +/- 5 km/h."

Use the actuator diagnosis function to set the value, and then adjust the needle accordingly?

Thank you for the tips. I'll try to put them into practice sometime this week.

Hello,

According to my observations, the speedometer reading is accurate up to just over 100 km/h. However, the needle's position doesn't quite match. It's not an absolute 5 km/h difference, but usually around 5%. Try driving at a constant speed of 100 km/h and reset the MFA, or connect a laptop to see the data more clearly. You'll see it more clearly that way.
In my test vehicles, the speed signal consistently matched the GPS signal up to speeds of over 100 km/h. However, at higher speeds, you can notice that the rolling circumference increases slightly due to centrifugal force. In this case, the GPS reading was higher than the speed signal, which essentially only counts the revolutions in the transmission.
It would be interesting if the deviation between the speedometer needle and the speed signal could be adjusted electronically.

Best regards, Matthias.

We also shouldn't forget what tire wear entails...

I know. But - a difference of 6 km/h at a speedometer reading of 50 km/h seems a bit excessive, I think.