Speedometer Calibration: Accurate & Reliable

Can anyone tell me if it's possible to change the speedometer reading using the VW diagnostic tool (1551)?
Unfortunately, after installing a TDI PD engine (ATD, year 2000) in my T3 van, I don't have a working speedometer.
The Hall sensor and speedometer from a Golf IV, as well as various other components from the donor vehicle, have been installed. The sensor is connected to the speedometer shaft. The displayed speed is exactly 50% lower than the actual speed.
A factor needs to be modified to double the incoming signal.
Best regards, Hoin.

Hello,

Could you please provide the part number of the combined device? That way, we can look it up.

Hello Michael,
I don't have any diagnostic tools, so I can't give you a number.
The possibility of programming the software was suggested to me by an electrical engineer.
I'm not familiar with using tools like VAG-COM or software like 1551.
Best regards, Hoin.

Hi,
The thing about the 50% display isn't that bad. You can quickly calculate how fast you are.
Does the odometer at least work, even if it's only half as fast?

Regards,
Eike.

"You're right, Eike, the odometer is also only showing half the correct mileage."
The other values, such as fuel consumption, average speed, and distance traveled, are also incorrect.
Hi.

Hi!

Under http://ha-projekt.de/, you can buy a frequency doubler for 49,- €.

Best regards,
Uwe