T4 TDI Speed Sensor Wiring Diagram ACV G22

Hello everyone, I recently bought a DRK T4 van, and it had a tachograph installed. The sensor for the tachograph had 4 wires, but I replaced it with the standard sensor G22, which only has 3 connections.
My question is, 'How is this connected when the connector is oriented with the rectangular coding facing downwards?'
Year of construction: 2003.

Hi,

There should be at least one number visible there!
The signal is definitely located in the center, while mass and a Kl.15 connector are found on the outside.
-> http://www.t4-wiki.de/wiki/G22