Cruise Control Wiring Diagram Sharan TDI 11/99

Hello everyone.

Does anyone have a wiring diagram for the cruise control system of a Sharan TDI with an 81 kW engine?
When I use VAG Com to check the cruise control, there is no reaction when I press the 'Set' button. I would like to quickly measure the switch, but VW is not providing me with a wiring diagram, even though my company generates 1000 Euros in revenue per month from that particular vehicle.

I hope someone here understands that you shouldn't have to pay 40 euros for an error code reading, and that someone can help me.

Thank you in advance, Julik.

Okay, let's start from the beginning.
Did you install an additional switch? If so, did you also activate the GRA (Gear Range Adapter)?